Teleologically, one might argue that inorganic cation and anion transport would be evolutionarily among the oldest transport functions. Eight families comprise the group that transports exclusively inorganic cations and anions across membranes : SLC4 plays a pivotal role in mediating Na+ - and/or Cl- -dependent transport of basic anions [e.g. HCO3-, (CO3)2-] in various tissues and cell types (in addition to pH regulation, specific members of this family also contribute to vectorial trans-epithelial base transport in several organ systems including the kidney, pancreas, and eye) (Pushkin A and Kurtz I, 2006); SLC8 is a group of Na+/Ca2+ exchangers (SLC8A1 is involved in cardiac contractility) (Quednau BD et al, 2004); SLC24 is a group of Na+/Ca2+ or Na+/K+ exchangers (Altimimi HF and Schnetkamp PP, 2007); SLC9 comprises Na+/H+ exchanger proteins involved in the electroneutral exchange of sodium ion and protons (Orlowski J and Grinstein S, 2004); SLC12 functions as Na+, K+ and Cl- ion electroneutral symporters (Hebert SC et al, 2004); SLC26 is the trans-epithelial multifunctional anion (e.g. sulfate, oxalate, HCO-, Cl-) exchanger family, important in cartilage development, production of thyroid hormone, sound amplification in the cochlea etc (Sindic A et al, 2007; Dorwart MR et al, 2008; Ashmore J, 2008). SLC34 is an important Type II Na+/(HPO4)2- symporter (Forster IC et al, 2006; Virkki LV et al, 2007); SLC20 was originally identified as a viral receptor, and functions as a Type III Na+/(H2PO4)- symporter (Collins JF et al, 2004; Virkki LV et al, 2007). Eight SLC gene families are involved in the transport of amino acids and oligopeptides.
View original pathway at:Reactome.
Dorwart MR, Shcheynikov N, Wang Y, Stippec S, Muallem S.; ''SLC26A9 is a Cl(-) channel regulated by the WNK kinases.''; PubMedEurope PMCScholia
Kamath SG, Furesz TC, Way BA, Smith CH.; ''Identification of three cationic amino acid transporters in placental trophoblast: cloning, expression, and characterization of hCAT-1.''; PubMedEurope PMCScholia
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Pfeiffer R, Rossier G, Spindler B, Meier C, Kühn L, Verrey F.; ''Amino acid transport of y+L-type by heterodimers of 4F2hc/CD98 and members of the glycoprotein-associated amino acid transporter family.''; PubMedEurope PMCScholia
Ramamoorthy S, Leibach FH, Mahesh VB, Han H, Yang-Feng T, Blakely RD, Ganapathy V.; ''Functional characterization and chromosomal localization of a cloned taurine transporter from human placenta.''; PubMedEurope PMCScholia
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Seow HF, Bröer S, Bröer A, Bailey CG, Potter SJ, Cavanaugh JA, Rasko JE.; ''Hartnup disorder is caused by mutations in the gene encoding the neutral amino acid transporter SLC6A19.''; PubMedEurope PMCScholia
Takanaga H, Mackenzie B, Peng JB, Hediger MA.; ''Characterization of a branched-chain amino-acid transporter SBAT1 (SLC6A15) that is expressed in human brain.''; PubMedEurope PMCScholia
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Gopal E, Umapathy NS, Martin PM, Ananth S, Gnana-Prakasam JP, Becker H, Wagner CA, Ganapathy V, Prasad PD.; ''Cloning and functional characterization of human SMCT2 (SLC5A12) and expression pattern of the transporter in kidney.''; PubMedEurope PMCScholia
Payne JA, Xu JC, Haas M, Lytle CY, Ward D, Forbush B.; ''Primary structure, functional expression, and chromosomal localization of the bumetanide-sensitive Na-K-Cl cotransporter in human colon.''; PubMedEurope PMCScholia
Matskevitch I, Wagner CA, Stegen C, Bröer S, Noll B, Risler T, Kwon HM, Handler JS, Waldegger S, Busch AE, Lang F.; ''Functional characterization of the Betaine/gamma-aminobutyric acid transporter BGT-1 expressed in Xenopus oocytes.''; PubMedEurope PMCScholia
Nakamura N, Tanaka S, Teko Y, Mitsui K, Kanazawa H.; ''Four Na+/H+ exchanger isoforms are distributed to Golgi and post-Golgi compartments and are involved in organelle pH regulation.''; PubMedEurope PMCScholia
Burnham CE, Amlal H, Wang Z, Shull GE, Soleimani M.; ''Cloning and functional expression of a human kidney Na+:HCO3- cotransporter.''; PubMedEurope PMCScholia
Igarashi T, Inatomi J, Sekine T, Cha SH, Kanai Y, Kunimi M, Tsukamoto K, Satoh H, Shimadzu M, Tozawa F, Mori T, Shiobara M, Seki G, Endou H.; ''Mutations in SLC4A4 cause permanent isolated proximal renal tubular acidosis with ocular abnormalities.''; PubMedEurope PMCScholia
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Pillai SM, Meredith D.; ''SLC36A4 (hPAT4) is a high affinity amino acid transporter when expressed in Xenopus laevis oocytes.''; PubMedEurope PMCScholia
Simon DB, Karet FE, Hamdan JM, DiPietro A, Sanjad SA, Lifton RP.; ''Bartter's syndrome, hypokalaemic alkalosis with hypercalciuria, is caused by mutations in the Na-K-2Cl cotransporter NKCC2.''; PubMedEurope PMCScholia
Vincourt JB, Jullien D, Kossida S, Amalric F, Girard JP.; ''Molecular cloning of SLC26A7, a novel member of the SLC26 sulfate/anion transporter family, from high endothelial venules and kidney.''; PubMedEurope PMCScholia
Agrimi G, Di Noia MA, Marobbio CM, Fiermonte G, Lasorsa FM, Palmieri F.; ''Identification of the human mitochondrial S-adenosylmethionine transporter: bacterial expression, reconstitution, functional characterization and tissue distribution.''; PubMedEurope PMCScholia
Feild JA, Zhang L, Brun KA, Brooks DP, Edwards RM.; ''Cloning and functional characterization of a sodium-dependent phosphate transporter expressed in human lung and small intestine.''; PubMedEurope PMCScholia
Molinari F, Raas-Rothschild A, Rio M, Fiermonte G, Encha-Razavi F, Palmieri L, Palmieri F, Ben-Neriah Z, Kadhom N, Vekemans M, Attie-Bitach T, Munnich A, Rustin P, Colleaux L.; ''Impaired mitochondrial glutamate transport in autosomal recessive neonatal myoclonic epilepsy.''; PubMedEurope PMCScholia
Hatanaka T, Huang W, Ling R, Prasad PD, Sugawara M, Leibach FH, Ganapathy V.; ''Evidence for the transport of neutral as well as cationic amino acids by ATA3, a novel and liver-specific subtype of amino acid transport system A.''; PubMedEurope PMCScholia
Anikster Y, Shotelersuk V, Gahl WA.; ''CTNS mutations in patients with cystinosis.''; PubMedEurope PMCScholia
Waldegger S, Moschen I, Ramirez A, Smith RJ, Ayadi H, Lang F, Kubisch C.; ''Cloning and characterization of SLC26A6, a novel member of the solute carrier 26 gene family.''; PubMedEurope PMCScholia
Fernandes I, Béliveau R, Friedlander G, Silve C.; ''NaPO(4) cotransport type III (PiT1) expression in human embryonic kidney cells and regulation by PTH.''; PubMedEurope PMCScholia
Bröer A, Wagner CA, Lang F, Bröer S.; ''The heterodimeric amino acid transporter 4F2hc/y+LAT2 mediates arginine efflux in exchange with glutamine.''; PubMedEurope PMCScholia
Corut A, Senyigit A, Ugur SA, Altin S, Ozcelik U, Calisir H, Yildirim Z, Gocmen A, Tolun A.; ''Mutations in SLC34A2 cause pulmonary alveolar microlithiasis and are possibly associated with testicular microlithiasis.''; PubMedEurope PMCScholia
Brant SR, Yun CH, Donowitz M, Tse CM.; ''Cloning, tissue distribution, and functional analysis of the human Na+/N+ exchanger isoform, NHE3.''; PubMedEurope PMCScholia
Kekuda R, Prasad PD, Fei YJ, Torres-Zamorano V, Sinha S, Yang-Feng TL, Leibach FH, Ganapathy V.; ''Cloning of the sodium-dependent, broad-scope, neutral amino acid transporter Bo from a human placental choriocarcinoma cell line.''; PubMedEurope PMCScholia
Vékony N, Wolf S, Boissel JP, Gnauert K, Closs EI.; ''Human cationic amino acid transporter hCAT-3 is preferentially expressed in peripheral tissues.''; PubMedEurope PMCScholia
Gasol E, Jiménez-Vidal M, Chillarón J, Zorzano A, Palacín M.; ''Membrane topology of system xc- light subunit reveals a re-entrant loop with substrate-restricted accessibility.''; PubMedEurope PMCScholia
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Takamori S, Malherbe P, Broger C, Jahn R.; ''Molecular cloning and functional characterization of human vesicular glutamate transporter 3.''; PubMedEurope PMCScholia
Vincourt JB, Jullien D, Amalric F, Girard JP.; ''Molecular and functional characterization of SLC26A11, a sodium-independent sulfate transporter from high endothelial venules.''; PubMedEurope PMCScholia
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van Zeijl M, Johann SV, Closs E, Cunningham J, Eddy R, Shows TB, O'Hara B.; ''A human amphotropic retrovirus receptor is a second member of the gibbon ape leukemia virus receptor family.''; PubMedEurope PMCScholia
Segawa H, Kaneko I, Takahashi A, Kuwahata M, Ito M, Ohkido I, Tatsumi S, Miyamoto K.; ''Growth-related renal type II Na/Pi cotransporter.''; PubMedEurope PMCScholia
Elmonem MA, Veys KR, Soliman NA, van Dyck M, van den Heuvel LP, Levtchenko E.; ''Cystinosis: a review.''; PubMedEurope PMCScholia
Fu C, Bardhan S, Cetateanu ND, Wamil BD, Wang Y, Yan HP, Shi E, Carter C, Venkov C, Yakes FM, Page DL, Lloyd RS, Mernaugh RL, Hellerqvist CG.; ''Identification of a novel membrane protein, HP59, with therapeutic potential as a target of tumor angiogenesis.''; PubMedEurope PMCScholia
Regeer RR, Lee A, Markovich D.; ''Characterization of the human sulfate anion transporter (hsat-1) protein and gene (SAT1; SLC26A1).''; PubMedEurope PMCScholia
Takanaga H, Mackenzie B, Suzuki Y, Hediger MA.; ''Identification of mammalian proline transporter SIT1 (SLC6A20) with characteristics of classical system imino.''; PubMedEurope PMCScholia
Numata M, Orlowski J.; ''Molecular cloning and characterization of a novel (Na+,K+)/H+ exchanger localized to the trans-Golgi network.''; PubMedEurope PMCScholia
Furesz TC, Heath-Monnig E, Kamath SG, Smith CH.; ''Lysine uptake by cloned hCAT-2B: comparison with hCAT-1 and with trophoblast surface membranes.''; PubMedEurope PMCScholia
Song L, Mercado A, Vázquez N, Xie Q, Desai R, George AL, Gamba G, Mount DB.; ''Molecular, functional, and genomic characterization of human KCC2, the neuronal K-Cl cotransporter.''; PubMedEurope PMCScholia
Botka CW, Wittig TW, Graul RC, Nielsen CU, Higaka K, Amidon GL, Sadée W.; ''Human proton/oligopeptide transporter (POT) genes: identification of putative human genes using bioinformatics.''; PubMedEurope PMCScholia
Smanik PA, Liu Q, Furminger TL, Ryu K, Xing S, Mazzaferri EL, Jhiang SM.; ''Cloning of the human sodium lodide symporter.''; PubMedEurope PMCScholia
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Saito H, Motohashi H, Mukai M, Inui K.; ''Cloning and characterization of a pH-sensing regulatory factor that modulates transport activity of the human H+/peptide cotransporter, PEPT1.''; PubMedEurope PMCScholia
Park SY, Kim JK, Kim IJ, Choi BK, Jung KY, Lee S, Park KJ, Chairoungdua A, Kanai Y, Endou H, Kim DK.; ''Reabsorption of neutral amino acids mediated by amino acid transporter LAT2 and TAT1 in the basolateral membrane of proximal tubule.''; PubMedEurope PMCScholia
Babu E, Kanai Y, Chairoungdua A, Kim DK, Iribe Y, Tangtrongsup S, Jutabha P, Li Y, Ahmed N, Sakamoto S, Anzai N, Nagamori S, Endou H.; ''Identification of a novel system L amino acid transporter structurally distinct from heterodimeric amino acid transporters.''; PubMedEurope PMCScholia
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Kleta R, Romeo E, Ristic Z, Ohura T, Stuart C, Arcos-Burgos M, Dave MH, Wagner CA, Camargo SR, Inoue S, Matsuura N, Helip-Wooley A, Bockenhauer D, Warth R, Bernardini I, Visser G, Eggermann T, Lee P, Chairoungdua A, Jutabha P, Babu E, Nilwarangkoon S, Anzai N, Kanai Y, Verrey F, Gahl WA, Koizumi A.; ''Mutations in SLC6A19, encoding B0AT1, cause Hartnup disorder.''; PubMedEurope PMCScholia
Rodriguez AM, Perron B, Lacroix L, Caillou B, Leblanc G, Schlumberger M, Bidart JM, Pourcher T.; ''Identification and characterization of a putative human iodide transporter located at the apical membrane of thyrocytes.''; PubMedEurope PMCScholia
Chiaverini C, Sillard L, Flori E, Ito S, Briganti S, Wakamatsu K, Fontas E, Berard E, Cailliez M, Cochat P, Foulard M, Guest G, Niaudet P, Picardo M, Bernard FX, Antignac C, Ortonne JP, Ballotti R.; ''Cystinosin is a melanosomal protein that regulates melanin synthesis.''; PubMedEurope PMCScholia
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Höglund P, Haila S, Socha J, Tomaszewski L, Saarialho-Kere U, Karjalainen-Lindsberg ML, Airola K, Holmberg C, de la Chapelle A, Kere J.; ''Mutations of the Down-regulated in adenoma (DRA) gene cause congenital chloride diarrhoea.''; PubMedEurope PMCScholia
Quan H, Athirakul K, Wetsel WC, Torres GE, Stevens R, Chen YT, Coffman TM, Caron MG.; ''Hypertension and impaired glycine handling in mice lacking the orphan transporter XT2.''; PubMedEurope PMCScholia
Kim DK, Kanai Y, Matsuo H, Kim JY, Chairoungdua A, Kobayashi Y, Enomoto A, Cha SH, Goya T, Endou H.; ''The human T-type amino acid transporter-1: characterization, gene organization, and chromosomal location.''; PubMedEurope PMCScholia
Fiermonte G, Dolce V, Arrigoni R, Runswick MJ, Walker JE, Palmieri F.; ''Organization and sequence of the gene for the human mitochondrial dicarboxylate carrier: evolution of the carrier family.''; PubMedEurope PMCScholia
Mizoguchi K, Cha SH, Chairoungdua A, Kim DK, Shigeta Y, Matsuo H, Fukushima J, Awa Y, Akakura K, Goya T, Ito H, Endou H, Kanai Y.; ''Human cystinuria-related transporter: localization and functional characterization.''; PubMedEurope PMCScholia
O'Hara B, Johann SV, Klinger HP, Blair DG, Rubinson H, Dunn KJ, Sass P, Vitek SM, Robins T.; ''Characterization of a human gene conferring sensitivity to infection by gibbon ape leukemia virus.''; PubMedEurope PMCScholia
Hatanaka T, Huang W, Wang H, Sugawara M, Prasad PD, Leibach FH, Ganapathy V.; ''Primary structure, functional characteristics and tissue expression pattern of human ATA2, a subtype of amino acid transport system A.''; PubMedEurope PMCScholia
Verheijen FW, Verbeek E, Aula N, Beerens CE, Havelaar AC, Joosse M, Peltonen L, Aula P, Galjaard H, van der Spek PJ, Mancini GM.; ''A new gene, encoding an anion transporter, is mutated in sialic acid storage diseases.''; PubMedEurope PMCScholia
Malakooti J, Dahdal RY, Schmidt L, Layden TJ, Dudeja PK, Ramaswamy K.; ''Molecular cloning, tissue distribution, and functional expression of the human Na(+)/H(+) exchanger NHE2.''; PubMedEurope PMCScholia
Arriza JL, Kavanaugh MP, Fairman WA, Wu YN, Murdoch GH, North RA, Amara SG.; ''Cloning and expression of a human neutral amino acid transporter with structural similarity to the glutamate transporter gene family.''; PubMedEurope PMCScholia
Porcelli V, Fiermonte G, Longo A, Palmieri F.; ''The human gene SLC25A29, of solute carrier family 25, encodes a mitochondrial transporter of basic amino acids.''; PubMedEurope PMCScholia
Sardet C, Franchi A, Pouysségur J.; ''Molecular cloning, primary structure, and expression of the human growth factor-activatable Na+/H+ antiporter.''; PubMedEurope PMCScholia
Forster IC, Köhler K, Biber J, Murer H.; ''Forging the link between structure and function of electrogenic cotransporters: the renal type IIa Na+/Pi cotransporter as a case study.''; PubMedEurope PMCScholia
Anderson CM, Ganapathy V, Thwaites DT.; ''Human solute carrier SLC6A14 is the beta-alanine carrier.''; PubMedEurope PMCScholia
Crompton M, Palmieri F, Capano M, Quagliariello E.; ''The transport of sulphate and sulphite in rat liver mitochondria.''; PubMedEurope PMCScholia
Ginger RS, Askew SE, Ogborne RM, Wilson S, Ferdinando D, Dadd T, Smith AM, Kazi S, Szerencsei RT, Winkfein RJ, Schnetkamp PP, Green MR.; ''SLC24A5 encodes a trans-Golgi network protein with potassium-dependent sodium-calcium exchange activity that regulates human epidermal melanogenesis.''; PubMedEurope PMCScholia
Yamaguchi S, Ishikawa T.; ''AHCYL2 (long-IRBIT) as a potential regulator of the electrogenic Na(+)-HCO3(-) cotransporter NBCe1-B.''; PubMedEurope PMCScholia
Baird NR, Orlowski J, Szabó EZ, Zaun HC, Schultheis PJ, Menon AG, Shull GE.; ''Molecular cloning, genomic organization, and functional expression of Na+/H+ exchanger isoform 5 (NHE5) from human brain.''; PubMedEurope PMCScholia
Forster IC, Loo DD, Eskandari S.; ''Stoichiometry and Na+ binding cooperativity of rat and flounder renal type II Na+-Pi cotransporters.''; PubMedEurope PMCScholia
Kishita Y, Pajak A, Bolar NA, Marobbio CM, Maffezzini C, Miniero DV, Monné M, Kohda M, Stranneheim H, Murayama K, Naess K, Lesko N, Bruhn H, Mourier A, Wibom R, Nennesmo I, Jespers A, Govaert P, Ohtake A, Van Laer L, Loeys BL, Freyer C, Palmieri F, Wredenberg A, Okazaki Y, Wedell A.; ''Intra-mitochondrial Methylation Deficiency Due to Mutations in SLC25A26.''; PubMedEurope PMCScholia
Rasola A, Galietta LJ, Barone V, Romeo G, Bagnasco S.; ''Molecular cloning and functional characterization of a GABA/betaine transporter from human kidney.''; PubMedEurope PMCScholia
Liu W, Liang R, Ramamoorthy S, Fei YJ, Ganapathy ME, Hediger MA, Ganapathy V, Leibach FH.; ''Molecular cloning of PEPT 2, a new member of the H+/peptide cotransporter family, from human kidney.''; PubMedEurope PMCScholia
Höglund PJ, Adzic D, Scicluna SJ, Lindblom J, Fredriksson R.; ''The repertoire of solute carriers of family 6: identification of new human and rodent genes.''; PubMedEurope PMCScholia
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Prié D, Huart V, Bakouh N, Planelles G, Dellis O, Gérard B, Hulin P, Benqué-Blanchet F, Silve C, Grandchamp B, Friedlander G.; ''Nephrolithiasis and osteoporosis associated with hypophosphatemia caused by mutations in the type 2a sodium-phosphate cotransporter.''; PubMedEurope PMCScholia
Chen Z, Fei YJ, Anderson CM, Wake KA, Miyauchi S, Huang W, Thwaites DT, Ganapathy V.; ''Structure, function and immunolocalization of a proton-coupled amino acid transporter (hPAT1) in the human intestinal cell line Caco-2.''; PubMedEurope PMCScholia
Fujiwara H, Tatsumi K, Miki K, Harada T, Miyai K, Takai S, Amino N.; ''Congenital hypothyroidism caused by a mutation in the Na+/I- symporter.''; PubMedEurope PMCScholia
Nakauchi J, Matsuo H, Kim DK, Goto A, Chairoungdua A, Cha SH, Inatomi J, Shiokawa Y, Yamaguchi K, Saito I, Endou H, Kanai Y.; ''Cloning and characterization of a human brain Na(+)-independent transporter for small neutral amino acids that transports D-serine with high affinity.''; PubMedEurope PMCScholia
Town M, Jean G, Cherqui S, Attard M, Forestier L, Whitmore SA, Callen DF, Gribouval O, Broyer M, Bates GP, van't Hoff W, Antignac C.; ''A novel gene encoding an integral membrane protein is mutated in nephropathic cystinosis.''; PubMedEurope PMCScholia
Bergwitz C, Roslin NM, Tieder M, Loredo-Osti JC, Bastepe M, Abu-Zahra H, Frappier D, Burkett K, Carpenter TO, Anderson D, Garabedian M, Sermet I, Fujiwara TM, Morgan K, Tenenhouse HS, Juppner H.; ''SLC34A3 mutations in patients with hereditary hypophosphatemic rickets with hypercalciuria predict a key role for the sodium-phosphate cotransporter NaPi-IIc in maintaining phosphate homeostasis.''; PubMedEurope PMCScholia
Aula N, Salomäki P, Timonen R, Verheijen F, Mancini G, Månsson JE, Aula P, Peltonen L.; ''The spectrum of SLC17A5-gene mutations resulting in free sialic acid-storage diseases indicates some genotype-phenotype correlation.''; PubMedEurope PMCScholia
Hästbacka J, de la Chapelle A, Mahtani MM, Clines G, Reeve-Daly MP, Daly M, Hamilton BA, Kusumi K, Trivedi B, Weaver A.; ''The diastrophic dysplasia gene encodes a novel sulfate transporter: positional cloning by fine-structure linkage disequilibrium mapping.''; PubMedEurope PMCScholia
Closs EI, Gräf P, Habermeier A, Cunningham JM, Förstermann U.; ''Human cationic amino acid transporters hCAT-1, hCAT-2A, and hCAT-2B: three related carriers with distinct transport properties.''; PubMedEurope PMCScholia
Bassi MT, Gasol E, Manzoni M, Pineda M, Riboni M, Martín R, Zorzano A, Borsani G, Palacín M.; ''Identification and characterisation of human xCT that co-expresses, with 4F2 heavy chain, the amino acid transport activity system xc-.''; PubMedEurope PMCScholia
Fiermonte G, Palmieri L, Todisco S, Agrimi G, Palmieri F, Walker JE.; ''Identification of the mitochondrial glutamate transporter. Bacterial expression, reconstitution, functional characterization, and tissue distribution of two human isoforms.''; PubMedEurope PMCScholia
Nakanishi T, Sugawara M, Huang W, Martindale RG, Leibach FH, Ganapathy ME, Prasad PD, Ganapathy V.; ''Structure, function, and tissue expression pattern of human SN2, a subtype of the amino acid transport system N.''; PubMedEurope PMCScholia
Prasad PD, Wang H, Huang W, Kekuda R, Rajan DP, Leibach FH, Ganapathy V.; ''Human LAT1, a subunit of system L amino acid transporter: molecular cloning and transport function.''; PubMedEurope PMCScholia
Kim KH, Shcheynikov N, Wang Y, Muallem S.; ''SLC26A7 is a Cl- channel regulated by intracellular pH.''; PubMedEurope PMCScholia
Howard HC, Mount DB, Rochefort D, Byun N, Dupré N, Lu J, Fan X, Song L, Rivière JB, Prévost C, Horst J, Simonati A, Lemcke B, Welch R, England R, Zhan FQ, Mercado A, Siesser WB, George AL, McDonald MP, Bouchard JP, Mathieu J, Delpire E, Rouleau GA.; ''The K-Cl cotransporter KCC3 is mutant in a severe peripheral neuropathy associated with agenesis of the corpus callosum.''; PubMedEurope PMCScholia
Wang H, Huang W, Sugawara M, Devoe LD, Leibach FH, Prasad PD, Ganapathy V.; ''Cloning and functional expression of ATA1, a subtype of amino acid transporter A, from human placenta.''; PubMedEurope PMCScholia
Mastroianni N, De Fusco M, Zollo M, Arrigo G, Zuffardi O, Bettinelli A, Ballabio A, Casari G.; ''Molecular cloning, expression pattern, and chromosomal localization of the human Na-Cl thiazide-sensitive cotransporter (SLC12A3).''; PubMedEurope PMCScholia
Miyauchi S, Gopal E, Fei YJ, Ganapathy V.; ''Functional identification of SLC5A8, a tumor suppressor down-regulated in colon cancer, as a Na(+)-coupled transporter for short-chain fatty acids.''; PubMedEurope PMCScholia
Bröer A, Wagner C, Lang F, Bröer S.; ''Neutral amino acid transporter ASCT2 displays substrate-induced Na+ exchange and a substrate-gated anion conductance.''; PubMedEurope PMCScholia
Zerangue N, Kavanaugh MP.; ''ASCT-1 is a neutral amino acid exchanger with chloride channel activity.''; PubMedEurope PMCScholia
Ni B, Du Y, Wu X, DeHoff BS, Rosteck PR, Paul SM.; ''Molecular cloning, expression, and chromosomal localization of a human brain-specific Na(+)-dependent inorganic phosphate cotransporter.''; PubMedEurope PMCScholia
Chong SS, Kristjansson K, Zoghbi HY, Hughes MR.; ''Molecular cloning of the cDNA encoding a human renal sodium phosphate transport protein and its assignment to chromosome 6p21.3-p23.''; PubMedEurope PMCScholia
Simon DB, Nelson-Williams C, Bia MJ, Ellison D, Karet FE, Molina AM, Vaara I, Iwata F, Cushner HM, Koolen M, Gainza FJ, Gitleman HJ, Lifton RP.; ''Gitelman's variant of Bartter's syndrome, inherited hypokalaemic alkalosis, is caused by mutations in the thiazide-sensitive Na-Cl cotransporter.''; PubMedEurope PMCScholia
Bröer S.; ''Amino acid transport across mammalian intestinal and renal epithelia.''; PubMedEurope PMCScholia
Schweinfest CW, Henderson KW, Suster S, Kondoh N, Papas TS.; ''Identification of a colon mucosa gene that is down-regulated in colon adenomas and adenocarcinomas.''; PubMedEurope PMCScholia
This CandidateSet contains sequences identified by William Pearson's analysis of Reactome catalyst entities. Catalyst entity sequences were used to identify analagous sequences that shared overall homology and active site homology. Sequences in this Candidate set were identified in an April 24, 2012 analysis.
The protein SLC6A18 was first identified as an amino acid transporter based on sequence similarity to other members of the SLC6 protein family (Hoglund et al. 2005). It is annotated here as mediating glycine uptake based on the phenotype of mice homozygous for a null mutation in the homologous gene (Quan et al. 2004).
The plasma membrane transport protein SLC6A6 mediates the uptake of taurine and beta-alanine. Together with each amino acid molecule, 2 sodium ions and 1 chloride ion are taken up. SLC6A6 is widely expressed in the body (Ramamoorthy et al. 1994).
The plasma membrane transport protein SLC6A12 (BGT-1) mediates the uptake of GABA (gamma-aminobutyrate) and betaine and, less efficiently, of diminobutyrate (DABA) and beta-alanine. Together with each amino acid molecule, 3 sodium ions and 2 chloride ions are taken up. In the body, SLC6A12 is expressed in the proximal tubules of the kidney and cells of the central nervous system (Rasola et al. 1995; Matskevitch et al. 1999).
SLC6A20, associated with the plasma membrane, mediates the uptake of proline plus a sodium ion. The human protein is expressed in the intestine and kidney (Takanaga et al. 2005).
SLC6A15, associated with the plasma membrane, mediates the uptake of a broad range of amino acids plus a sodium ion, transporting branched-chain amiono acids and methionine most efficiently. The human protein is expressed in the brain (Takanaga et al. 2005).
SLC43A1 (LAT3), associated with the plasma membrane, mediates the uptake of isoleucine, leucine, methionine, phenylalanine, and valine in a biphasic and sodium ion-independent transport process. Northern blotting experiments indicate gene expression in liver, pancreas, and skeletal muscle, and at lower levels in many tissues including kidney and intestine (Babu et al. 2003).
SLC43A2 (LAT4), associated with the plasma membrane, mediates the uptake of isoleucine, leucine, methionine, phenylalanine, and valine in a biphasic and sodium ion-independent transport process. Northern blotting and in situ hybridization experiments indicate gene expression in kidney and intestine (Bodoy et al. 2005).
SLC38A2 (ATA2), associated with the plasma membrane, mediates the uptake of neutral amino acids, especially alanine, asparagine, glutamine, glycine, leucine, methionine, proline, and threonine in a sodium ion-dependent transport process. Northern blotting experiments indicate gene expression in placenta and heart, and at lower levels in other tissues including brain, lung, skeletal muscle, spleen, stomach, testis, kidney, and intestine (Hatanaka et al. 2000).
SLC38A1 (ATA1), associated with the plasma membrane, mediates the uptake of neutral amino acids, especially alanine, asparagine, glutamine, methionine, and serine in a sodium ion-dependent transport process. Northern blotting experiments indicate gene expression in placenta and heart, and at lower levels in other tissues including brain, lung, skeletal muscle, spleen, stomach and testis, but not kidney or intestine (Wang et al. 2000).
SLC38A4 (ATA3), associated with the plasma membrane, mediates the sodium-independent uptake of arginine and lysine. SLC38A4 was first identified on the basis of its similarity to SLC38A1 and SLC38A2. Like those two transporters, it can mediate the sodium-dependent uptake of neutral amino acids in cultured cells transfected with an expression vector, but it does so very inefficiently and its role, if any, in neutral amino acid uptake in vivo is unclear. By Northern blotting, SLC38A4 is abundant in liver and undetectable in all other tissues tested, including heart, placenta, kidney, and intestine (Hatanaka et al. 2001).
SLC16A10 mediates the reversible facilitated diffusion of phenylalanine, tyrosine, and tryptophan across the plasma membrane. The process is Na+-independent and not coupled to H+ transport. As measured by Northern blotting SLC16A10 is widely expressed in the body but especially abundant in kidney. In situ hybridization studies indicate that the gene product is abundant in kidney proximal tubules (Kim et al. 2001; Kim et al. 2002; Park et al. 2005).
SLC38A3 (SN1), associated with the plasma membrane, mediates the uptake of glutamine, histidine, and, with lower efficiency, alanine and asparagine. Uptake of one molecule of amino acid is coupled to the uptake of two sodium ions and the export of one H+. Northern blotting experiments indicate gene expression in liver and kidney, and at much lower levels in brain, lung, skeletal muscle, spleen, stomach, testis, kidney, and intestine (Fei et al. 2000; Nakanishi et al. 2001).
SLC38A5 (SN2), associated with the plasma membrane, mediates the uptake of asparagine, glutamine, histidine, serine and, with lower efficiency, alanine and glycine. Indirect assays suggest that amino acid uptake is coupled to the uptake of sodium ion(s) and the export of H+. Northern blotting experiments indicate gene expression in brain and stomach, and at lower levels in liver, lung, and intestine (Nakanishi et al. 2001).
SLC7A8, complexed with SLC3A2 in the plasma membrane, mediates the uptake of neutral amino acids. The process is Na+-independent and not coupled to H+ transport. As measured by Northern blotting SLC7A8 is widely expressed in the body. In situ hybridization studies indicate that the gene product is abundant in kidney proximal tubules (Pineda et al. 1999; Park et al. 2005)
SLC7A5, complexed with SLC3A2 in the plasma membrane, mediates the uptake of neutral amino acids. The process is Na+-independent and not coupled to H+ transport. As measured by Northern blotting SLC7A5 is widely expressed in the body. In situ hybridization studies indicate that the gene product is widely expressed in the body but not in the kidney (Pineda et al. 1999; Prasad et al. 1999).
SLC1A4, associated with the plasma membrane, mediates the exchange of serine and an extracellular sodium ion for a cytosolic sodium ion and any one of the four amino acids alanine, serine, threonine, or cysteine (Zerangue and Kavanaugh 1996).
SLC1A4, associated with the plasma membrane, mediates the exchange of cysteine and an extracellular sodium ion for a cytosolic sodium ion and any one of the four amino acids alanine, serine, threonine, or cysteine (Zerangue and Kavanaugh 1996).
SLC1A4, associated with the plasma membrane, mediates the exchange of alanine and an extracellular sodium ion for a cytosolic sodium ion and any one of the four amino acids alanine, serine, threonine, or cysteine (Zerangue and Kavanaugh 1996).
SLC1A4, associated with the plasma membrane, mediates the exchange of threonine and an extracellular sodium ion for a cytosolic sodium ion and any one of the four amino acids alanine, serine, threonine, or cysteine (Zerangue and Kavanaugh 1996).
SLC25A10, the mitochondrial dicarboxylate carrier protein in the inner mitochondrial membrane, mediates the reversible exchange of mitochondrial malate for cytosolic phosphate (Fiermonte et al. 1999).
SLC36A2 (PAT2), associated with the plasma membrane, has been shown in a limited set of tests in vitro to mediate the uptake of glycine and proline coupled to the uptake of a proton (Boll et al. 2003). PAT2 is most abundantly expressed in kidney and muscle.
SLC36A1 (PAT1), associated with the plasma membrane, mediates the uptake of glycine, alanine, and proline coupled to the uptake of a proton. Northern blotting experiments indicate gene expression principally in the intestine (Chen et al. 2003).
SLC6A19 mediates the uptake of neutral amino acids across the plasma membrane. Uptake of an amino acid molecule is accompanied by uptake of a sodium ion. The protein is abundant in cells in the small intestine and kidney. Its deficiency is associated with Hartnup disorder, the failure to take up neutral amino acids efficiently from the gut lumen and to reabsorb them in the proximal kidney tubule (Kleta et al. 2004, Seow et al. 2004).
SLC6A14, associated with the plasma membrane, mediates the uptake of multiple basic and nonpolar amino acids as well as beta-alanine. Uptake of one amino acid molecule is accompanied by uptake of two sodium ions and a chloride ion. As assessed by Northern blotting, SLC6A14 is expressed at high levels in lung but only at low levels, if at all, in intestine or kidney (Sloan & Mager 1999, Anderson et al. 2008).
SLC7A2, isoform B, mediates the uptake of cationic amino acids across the plasma membranes of non-epithelial cells (Broer 2008; Closs et al. 1997; Furesz et al. 2002).
SLC7A1 mediates the uptake of cationic amino acids across the plasma membranes of non-epithelial cells (Broer 2008; Closs et al. 1997; Furesz et al. 2002; Kamath et al. 1999).
SLC7A10, complexed with SLC3A2 in the plasma membrane, mediates the uptake of small neutral amino acids. The process is Na+-independent. As measured by Northern blotting SLC7A10 is widely expressed in the body (Nakauchi et al. 2000).
SLC7A11 as a heterodimer with SLC3A2 in the plasma membrane mediates the exchange of glutamate and cysteine. Under physiological conditions, cytosolic glutamate concentrations are high and cysteine concentrations are low, so glutamate is exported and cysteine imported. SLC7A11 is widely expressed in the body (Bassi et al. 2001; Gasol et al. 2004).
SLC7A7 as a heterodimer with SLC3A2 in the plasma membrane mediates the exchange of arginine (L-Arg) for leucine (L-Leu) and a sodium ion (Na+). The physiological concentrations of arginine and leucine are expected to favor arginine export. By the criterion of Northern blotting, SLC7A6 is predominantly expressed in the kidney (Pfeiffer et al. 2000).
SLC7A6 as a heterodimer with SLC3A2 in the plasma membrane mediates the exchange of arginine for leucine and a sodium ion. The physiological concentrations of arginine and leucine are expected to favor arginine export. By the criterion of Northern blotting, SLC7A6 is expressed in a variety of tissues (Broer et al. 2000).
SLC7A9 as a heterodimer with SLC3A1 in the plasma membrane mediates the exchange of arginine (L-Arg), lysine (L-Lys), or cystine (CySS-) for leucine (L-Leu) and other neutral amino acids. The physiological concentrations of these amino acids favor neutral amino acid export and arginine/lysine/cystine import. Defects in SLC7A9 and SLC3A1 cause cystinuria. In the body, this transport process is prominent in the kidney (Mizoguchi et al. 2001).
The proteins responsible for the exchange of Cl- with HCO3- are members of the SLC4 (1-3) and SLC26 (3, 4, 6, 7 and 9) transporter families. The SLC26 members are discussed under the section "Multifunctional anion exchangers".
SLC4A1 (Band 3, AE1, anion exchanger 1) was the first bicarbonate transporter gene to be cloned and sequenced (Lux et al. 1989). It is ubiquitous throughout vertebrates and in humans, is present on erythrocytes and the basolateral surfaces of kidney cells. The erythrocyte and kidney forms are different isoforms of the same protein (Kollert-Jons et al. 1993). Variations in erythroid AE1 determine the Diego blood group system (Bruce et al. 1994). A more serious consequence of mutated erythroid AE1 is Hereditary spherocytosis (a disorder leading to haemolytic anaemia) (Jarolim et al. 1995). Defects in the kidney form of AE1 cause distal (type1) renal tubular acidosis (an inability to acidify urine) (Bruce et al. 1997).
SLC4A2 (Non-erythroid band 3-like protein, AE2, anion exchanger 2) is widely expressed and is considered to be the 'housekeeping' isoform of the bicarbonate transporters (Demuth et al. 1986). SLC4A3 (Cardiac/brain band 3-like protein, AE3) is expressed in heart and brain (Yannoukakos et al. 1994).
Members of the SLC4A family couple the transport of bicarbonate (HCO3-) with sodium ions (Na+); they being members 4, 5, 7 and 9. SLC4A5 encodes a protein which is expressed in liver, spleen and testes, with lower levels expressed in parts of the brain and kidney (Sassani et al. 2002). It may have a housekeeping function in regulating the pH of these tissues (Pushkin et al. 2000).
SLC4A7 (aka NBC3, NBCn1) encodes a protein which performs electroneutral cotransport of Na+ and HCO3- with a 1:1 stoichiometry. It is highly expressed in testes and spleen and, to a lesser extent, in many other tissues including heart, muscle, kidney and GI tract (Pushkin et al. 1999).
SLC4A9 (aka AE4) was originally thought to exchange Cl- with HCO3- (hence the name AE4) but this has not been reported. Consensus has emerged that it is indeed a Na+/HCO3- co-transporter (Lipovich et al. 2001). It is predominantly expressed in the kidney, salivary glands, testes, thyroid glands and trachea (Parker et al. 2001).
Two genes encode Na+-dependent Cl-/HCO3- exchangers; SLC4A8 (NDCBE1) and 10 (NCBE). SLC4A8 (NDCBE1) encodes a exchanger protein which mediates Na+:HCO3- transport with a stoichiometry of 1:2:1 (Na+/HCO3-/Cl-). This protein is highly expressed in brain and spine and moderately expressed in trachea, thyroid, and kidney (Amlal H et al, 1999). SLC4A10 (NCBE, NBCn2) encodes a Na+-driven Cl-/HCO3- exchanger protein (Parker MD et al, 2008). It transports extracellular Na+ and HCO3- into cells in exchange for intracellular Cl- and H+, thus raising the intracellular pH.
The sodium/calcium exchangers 1, 2 and 3 (SCL8A1,2,3 aka NCX1,2,3) belong to one of three families that control Ca2+ flux across the plasma membrane or intracellular compartments. They extrude Ca2+ from the cell, using the electrochemical gradient of Na+ as it flows into the cell. One Ca2+ is exchanged for three Na+. During this electrogenic exchange, the membrane potential is altered. SLC8A1, 2, 3 play a minor role during phase 2, since they begin to restore ion concentrations. The high concentration of intracellular calcium starts contraction of those cells, which is sustained in the plateau phase. SLC8A1 has a ubiquitous expression profile (highest expression in heart, brain and kidney) and was originally cloned and characterized from human cardiac muscle (Komuro et al. 1992). Both SLC8A2) (Li et al. 1994) and SLC8A3 (Gabellini et al. 2002) are expressed in the brain. In Rabbits, sorcin (SRI) activates SLC8A1, via the interaction of the respective Ca2+-binding domains (Zamparelli et al. 2010). Calmodulin (CALM1) binds to the cytoplasmic loop of NCX1 to negatively regulate exchange activity (Chou et al. 2015).
The five members of the NCKX (SLC24) family are all able to exchange one Ca2+ and one K+ for four Na+. NCKX1 (SLC24A1) encodes an exchanger protein which is the most extensively studied member (Tucker et al. 1998). It is highly expressed in the eye. Other members are expressed in the brain and skin as well as the eye (Prinsen et al. 2000, Kraev et al. 2001, Li et al. 2002, Lamason et al. 2005).
SLC24A6 (NCKX6, NCLX) (Palty R et al, 2004) encodes a protein which can transport Li+ or Na+ in exchange for Ca2+ in an K+-independent manner (Cai X and Lytton J, 2004). Lithium exchange with calcium is shown here.
NHE6 (SLC9A6) (Brett CL et al, 2002; Nakamura N et al, 2005) is expressed ubiquitously and thought to play a housekeeping role in pH homeostasis in early endosomes.
NHE1 (SLC9A1) is present in most cells and is the most extensively characterized member of this family (Sardet C et al, 1989). NHE2-4 (SLC9A2-4) (Malakooti J et al, 1999; Brant SR et al, 1995) are expressed mainly in the kidney and GI tract. NHE5 (SLC9A5) (Baird NR et al, 1999) is highly expressed in neuronal-enriched areas of the CNS.
NHE7 and 8 (SLC9A7,8) (Nakamura N et al, 2005) are expressed ubiquitously and thought to play a housekeeping role in pH homeostasis in the trans-golgi network.
Two genes (SLC12A1 and SLC12A2) encode Na+,K+/2Cl- cotransporters (NKCC2 and NKCC1 respectively). SLC12A1 (Simon DB et al, 1996) is kidney-specific whilst SLC12A2 (Payne JA et al, 1995) is ubiquitously expressed. Two Cl- ions are electroneutrally transported into cells with a Na+ ion and a K+ ion.
The SLC12A3 gene encodes for the Thiazide-sensitive sodium-chloride cotransporter (TSC). TSC mediates sodium and chloride removal from the distal convoluted tubule of the kidney (Mastroianni N et al, 1996). Defects in SLC12A3 are the cause of Gitelman syndrome (GS). GS is an autosomal recessive disorder that allows the kidneys to pass sodium, magnesium, chloride, and potassium into the urine, rather than being reabsorbed into the bloodstream (Simon et al. 1996). This cotransporter is the major target for thiazide-type diuretics, used in the treatment of hypertension, extracellular fluid overload and renal stone disease.
K+/Cl- cotransport is implicated not only in regulatory volume decrease, but also in transepithelial salt absorption, renal K+ secretion, myocardial K+ loss during ischemia and regulation of neuronal Cl- concentration. Four genes (SLC12A4-7) encode the K+/Cl- cotransporters KCC1-4 respectively. Cotransport of K+ and Cl- is electroneutral with a 1:1 stoichiometry. These cotransporters function as homomultimers or heteromultimers with other K+/Cl- cotransporters. SLC12A4 encodes KCC1 (Gillen CM et al, 1996). KCC1 is ubiquitously expressed, suggesting a housekeeping role in the regulation of cell volume. SLC12A5 encodes KCC2 (Song L et al, 2002). KCC2's expression is restricted to neurons in the CNS and retina. It is thought KCC2 is important for Cl- homeostasis in neurons. SLC12A6 encodes KCC3 (Race JE et al, 1999; Mount DB et al, 1999). KCC3 is highly expressed in heart, brain, spinal cord, kidney, muscle, pancreas and placenta. Defects in SLC12A6 are a cause of agenesis of the corpus callosum with peripheral neuropathy (ACCPN) (Howard HC et al, 2002). SLC12A7 encodes KCC4 (Mount DB et al, 1999) which is widely expressed, especially in the kidney. It is thought to play a role in transepithelial transport of Cl- by the proximal tubule.
The SLC26A1 and 2 genes encode proteins that facilitate sulfate (SO4(2-)) uptake into cells (Alper & Sharma 2013). The mechanism by which these transporters work is unclear but may be enhanced by extracellular halides or acidic pH environments, cotransporting protons electroneutrally. Both can transport SO4(2-) (as well as oxalate and Cl-) across the basolateral membrane of epithelial cells. SLC26A1 encodes the sulfate anion transporter 1 (SAT1) (Regeer et al. 2003) and is most abundantly expressed in the liver and kidney, with lower levels expressed in many other parts of the body. SLC26A2 is ubiquitously expressed and encodes a sulfate transporter (Diastrophic dysplasia protein, DTD, DTDST) (Hastbacka et al. 1994). This transporter provides sulfate for sulfation of glycosaminoglycan chains in proteoglycans needed for cartilage development. Defects in SLC26A2 are implicated in the pathogenesis of several human chondrodysplasias.
Group 3 members (SLC26A7 and 9) function as ion channels. SLC26A7 encodes an ion channel which is abundantly expressed in medullary collecting duct cells of the kidney, high endothelial venule enothelial cells (HEVEC) and gastric parietal cells (Vincourt JB et al, 2002; Lohi H et al, 2002). SLC26A9 encodes an ion channel which is predominantly expressed on the lumenal side of the bronchiolar and alveolar epithelium of lung (Lohi H et al, 2002). Both these ion channels appear to transport Cl- without cotransport of HCO3- (Kim KH et al, 2005; Dorwart MR et al, 2007).
There are two transporters of this type; The genes SLC20A1 and SLC20A2 encode for phosphate transporters 1 and 2 (PiT1 and PiT2 respectively). They both have a broad tissue distribution and may play a general housekeeping role in phosphate transport such as absorbing phosphate from interstitial fluid and in extracellular matrix and cartilage calcification as well as in vascular calcification. These proteins were originally described as retroviral receptors for the gibbin ape leukemia virus receptor 1 (GLVR1, now called PiT1) (O'Hara et al. 1990) and GLVR2 (now called PiT2) (van Zeijl et al.1994). However, they were found to possess Na+-coupled phosphate cotransporter function (Fernandes et al. 1999). The transport is electrogenic with a stoichiometry of 2:1 (Na+:Pi).
SLC34A3 is almost exclusively expressed in the kidney and encodes the Na+/Pi cotransporter NaPi-IIc (Segawa et al. 2002). The protein is located at apical membranes of proximal tubules. It cotransports two Na+ ions with every Pi (electroneutral transport). Defects in SLC34A3 are the cause of hereditary hypophosphatemic rickets with hypercalciuria (HHRH) (Bergwitz et al. 2006).
SLC34A1 encodes Na+/Pi cotransporter (NaPi-IIa) which is expressed in the kidney in the renal proximal tubule (Magagnin et al. 1993). SLC34A2 encodes NaPi-IIb which is abundantly expressed in lung and to a lesser degree in tissues of epithelial origin including small intestine, pancreas, prostate, and kidney (Field et al. 1999). In the lung, SLC34A2 is expressed only in alveolar type II cells, which are responsible for surfactant production, so it is proposed that it uptakes liberated phosphate from the alveolar fluid for surfactant production. Both NaPi-IIa and NaPi-IIb cotransport divalent phosphate (HPO4(2-)) with three Na+ ions (electrogenic transport) (Forster et al. 1999, 2002).
Defects in SLC34A1 are the cause of hypophosphatemic nephrolithiasis/osteoporosis type 1 (NPHLOP1) (Prie et al. 2002). Defects in SLC34A2 are a cause of pulmonary alveolar microlithiasis, a rare disease characterised by the deposition of calcium phosphate microliths throughout the lung (Corut et al. 2006).
The proteins responsible for the exchange of chloride (Cl-) with bicarbonate (HCO3-) are members of the SLC4 (1-3) and SLC26 (3 and 6) transporter families. SLC4 members are discussed in the section "Bicarbonate transporters".
SLC26A3 (Chloride anion exchanger, Down-regulated in adenoma, DRA) is expressed in the mucosa of the colon and helps mediate electrolyte and fluid absorption (Schweinfest et al. 1993). Defects in SLC26A3 cause congenital chloride diarrhea 1 (DIAR1), a disease characterized by watery stools containing an excess of chloride (Hoeglund et al. 1996). SLC26A6 encodes a protein involved in transporting chloride, oxalate, sulfate and bicarbonate (Waldegger et al. 2001). It is ubiquitously expressed, the highest levels present in kidney and pancreas.
The prototypical transporters of the SLC15 gene family are PEPT1 and PEPT2, which mediate the uptake of every possible di- and tri-peptide. PEPT1 (PTR1) is expressed mainly in the intestine (Liang R et al, 1995; Saito H et al, 1997) while PEPT2 (PTR2) is expressed in the kidney (Liu W et al, 1995).
A bioinformatics approach identified two further human transporters, PHT1 and PHT2 (Botka CW et al, 2000). These two transporters may be located on the lysosomal membrane for the proton-coupled export of histidine and di-peptides from lysosomal protein degradation.
There are two classes of glutamate transporters; the excitatory amino acid transporters (EAATs) which depend on an electrochemical gradient of Na+ ions and vesicular glutamate transporters (VGLUTs) which are proton-dependent. Together, these transporters uptake and release glutamate to mediate this neurotransmitter's excitatory signal and are part of the glutamate-gluatamine cycle.
The SLC1 gene family includes five high-affinity glutamate transporters encoded by SLC1, 2, 3, 6 and 7. These transporters can mediate transport of L-Glutamate, L-Aspartate and D-Aspartate with cotransport of 3 Na+ ions and H+ and antiport of a K+ ion. This mechanism allows glutamate into cells against a concentration gradient. This is a crucial factor in the protection of neurons against glutamate excitotoxicity in the CNS.
SLC1A1 encodes an excitatory amino-acid carrier 1 (EAAC1, also called EAAT3) (Shashidharan et al. 1994, Arriza et al. 1994) and is abundant particularly in brain but also in liver, muscle, ovary, testis and in retinoblastoma cell lines. In the kidney, EAAC1 is present at apical membranes of proximal tubes. Defects in SLC1A1 are the cause of dicarboxylic aminoaciduria (glutamate-aspartate transport defect in the kidney and intestine). SLC1A2 encodes the glial-type high affinity glutamate transporter (GLT1, EAAT2) (Arriza et al. 1994). GLT1 is expressed mainly in the brain and is essential for terminating the postsynaptic action of glutamate by rapidly removing released glutamate from the synaptic cleft.
SLC1A3 encodes a sodium-dependent glutamate/aspartate transporter 1 (GLAST1, EAAT1). It is particularly abundant in the cerebellum and, like GLT1, plays a role in terminating the postsynaptic action of glutamate (Arriza JL et al, 1994). Defects in SLC1A3 are the cause of episodic ataxia type 6 (EA6), characterized by episodic ataxia, seizures, migraine and alternating hemiplegia (Jen JC et al, 2005).
SLC1A6 encodes an excitatory amino-acid transporter 4 (EAAT4) (Fairman WA et al, 1995) and is predominantly expressed in cerebellar Purkinje cells. SLC1A7 encodes an excitatory amino acid transporter 5 (EAAT5, retinal glutamate transporter) (Arriza JL et al, 1997) which is highly expressed in the retina.
There are two classes of glutamate transporters; the excitatory amino acid transporters (EAATs) which depend on an electrochemical gradient of Na+ ions and vesicular glutamate transporters (VGLUTs) which don't. Together, these transporters uptake and release glutamate to mediate this neurotransmitter's excitatory signal and are part of the glutamate-gluatamine cycle.
Three members of the SLC17A gene family (7, 6 and 8) encode VGLUTs 1-3 respectively (Ni et al. 1996, Takamori et al. 2001, Takamori et al. 2002 respectively). VGLUT1 (brain-specific Na+-dependent phopshate transporter, BNPI) and VGLUT2 (differentiation-associated Na+-dependent phosphate transporter, DNPI) were identified first and originally characterized as phosphate transporters. However, they are localized to synaptic vesicles, not the plasma membrane (like EAATs) and transport the organic anion glutamate into synaptic vesicles. This uptake is thought to be coupled to the proton electrochemical gradient generated by a vacuolar type H+-ATPase. They are all expressed in the CNS in neuron-rich areas but VGLUT3 is also expressed on astrocytes and in liver and kidney.
SLC17A5 encodes a lysosomal sialic acid transporter, Sialin (AST, membrane glycoprotein HP59) (Verheijen et al. 1999, Fu et al. 2001). SLC17A5 exports sialic acid (N-acetylneuraminic acid, Neu5Ac) which is derived from the degradation of glycoconjugates. This export is dependent on the proton electrochemical gradient across the lysosomal membrane. SLC17A5 is present in the pathological tumor vasculature of the lung, breast, colon, and ovary, but not in the normal vasculature, suggesting that the protein may be critical to pathological angiogenesis. Sialin is not expressed in a variety of normal tissues, but is significantly expressed in human fetal lung. Defects in SLC17A5 cause Salla disease (SD) and infantile sialic acid storage disorder (ISSD aka N-acetylneuraminic acid storage disease, NSD). These belong to the sialic acid storage disease (SASD) group and are autosomal recessive neurodegenerative disorders characterised by hypotonia, cerebellar ataxia and mental retardation in very young infants (Verheijen et al. 1999, Aula et al. 2000).
Four SLC17 genes are thought to encode type I Na+-dependent phosphate co-transporters in humans. SLC17A1 (NPT1) encodes Na+-dependent phosphate co-transporter 1 (Na/Pi-4). It is abundant in human kidney cortex, liver and brain and is important for the resorption of phosphate by the kidney. It does this by actively transporting phosphate into cells via Na+ cotransport in the renal brush border membrane (Chong SS et al, 1993).
Three close relatives of NPT1 have been identified through genomic analysis and designated NPT3 (SLC17A2), NPT4 (SLC17A3) and a putative small intestine sodium-dependent phosphate co-transporter (SLC17A4). None of these three proteins have been functionally characterized yet.
Gamma-Aminobutyric acid (GABA) is the major inhibitory transmitter of the vertebrate retina. The gene SLC32A1 encodes the vesicular inhibitory amino acid transporter (VIAAT, also called vesicular GABA transporter VGAT) (Jellali A et al, 2002). VIAAT is a proton-coupled amino acid antiporter, uptaking the inhibitory neurotransmitters GABA and glycine into synaptic vesicles in exchange for protons. This process is driven by the H+-ATPase, providing the driving force for uptake of these neurotransmitters. The protein is expressed throughout the terminal ends of horizontal cells of the retina.
Human SLC5A5 encodes a Na+/I- symporter, NIS (Smanik et al. 1996). NIS is localized in the basolateral membrane facing the bloodstream and mediates iodide accumulation into thyrocytes. Defects in SLC5A5 cause congenital hypothyroidism due to dyshormonogenesis type 1 (CHDH1) (Fujiwara et al. 1997). NIS, together with AIT (see next reaction), mediates iodide transfer from blood to the colloid lumen of thyrocytes.
The human tumour suppressor gene SLC5A8 encodes sodium-coupled monocarboxylate transporter 1, SMCT1 (also called AIT) and is abundantly expressed in the colon (Coady et al. 2004, Myauchi et al. 2004). When the human protein is expressed in Xenopus oocytes, it was found to transport small monocarboxylates and carboxylate drugs, co-transporting Na+ ions electrogenically (3 Na+ ions co-transported with 1 carboxylate).
SLC5A8 encodes for the apical iodide transporter, AIT (also known as SMCT1). As well as functioning as a Na+-dependent monocarboxylate co-transporter, AIT also mediates iodide transport from the thyrocyte into the colloid lumen through the apical membrane (Rodriguez AM et al, 2002). AIT, together with NIS (see previous reaction), mediates iodide transfer from blood to the colloid lumen of thyrocytes.
Cystinosin (CTNS) is an integral lysosomal membrane protein which can transport L-cystine (CySS-, the oxidative product of two cysteine molecules linked via a disulfide bond) together with H+ out of lysosomes. CySS- is a component of hair, skin and nails. Defects in CTNS cause cystinosis, lysosomal storage-type diseases due to defective transport of CySS- across the lysosomal membrane (Town et al. 1998, Anikster et al. 1999; review Elmonem et al. 2016). Patients with cystinosis frequently exhibit blond hair and a fair complexion, suggesting an involvement in melanogenesis. Chiaverini et al. show CTNS is also localised to melanosomes. CTNS silencing led to a 75% reduction of melanin synthesis, caused by a degradation of tyrosinase (the enzyme responsible for melanin biosynthesis), thereby identifying a role for CTNS in melanogenesis (Chiaverini et al. 2012).
The five members of the NCKX (SLC24) family are all able to exchange one Ca2+ and one K+ for four Na+. SLC24A5 encodes a trans-Golgi network exchanger protein NCKX5 which is expressed in melanocytes and regulates human epidermal melanogenesis (Ginger et al. 2008).
SLC26 members A3, 4 and 6 are able to exchange chloride for bicarbonate. SLC26A4 (Pendrin) can also mediate the efflux of iodide (I-) from the apical membranes of thyroid and inner ear cells. SLC26A4 is highly expressed in the adult thyroid and its activity is necessary for production of thyroid hormone (Dossena et al. 2006). Mutations in this gene are associated with Pendred syndrome, an autosomal-recessive disease which is the most common form of syndromic deafness and associated goitre.
SLC25A26 (S-adenosylmethionine mitochondrial carrier protein) associated with the inner mitochondrial membrane mediates the exchange of cytosolic AdoMet (S-adenosylmethionine) for mitochondrial AdoHcy (S-adenosylhomocysteine). The substrate specificity and countertransport function of SLC25A26 were established from studies of liposomes reconstituted with purified protein in vitro (Agrimi et al. 2004). SLC25A26 mutations that disrupt transport activity have been identified in patients with defects of mitochondrial function, consistent with a requirement for AdoMet uptake from the cytosol to support mitochondrial methylation reactions (Kishita et al. 2015).
Plasma membrane-associated SLC36A4 (solute carrier family 36 member 4, also known as PAT4 - proton-coupled amino acid transporter 4) mediates the uptake of extracellular L-Pro (L-proline) (Pillai & Meredith 2011).
Mitochondrial glutamate carriers 1 and 2 (SLC25A22, GC1 and SLC25A18, GC2) belong to the mitochondrial carrier family of transport proteins which shuttle substrates, metabolites and cofactors through the mitochondrial membrane, connecting the cytosol to the mitochondrial matrix. Glutamate (Glu) can be co-transported with H+ via SLC25A18 and SLC25A22, located on the inner mitochondrial membrane (Fiermonte et al. 2002). Defects in SLC25A22 can cause early infantile epileptic encephalopathy 3 (EIEE3; MIM:609304), a severe neonatal epilepsy characterised by a very early onset, erratic and fragmentary myoclonus. With no treatment available, children with EIEE3 die within 1 or 2 years of birth or survive in a vegetative state (Molinari et al. 2005).
Lymphocytes migrate from the blood into most secondary lymphoid organs and chronically inflamed tissues through high endothelial venules (HEV). HEV endothelial cells (HEVECs) incorporate large amounts of sulfate into sialomucin-type counter-receptors for the lymphocyte-homing receptor L-selectin. Sulfate uptake into HEVECs is mediated by two functionally-distinct classes of sulfate transporters: Na+-coupled transporters and sulfate/anion exchangers. Sodium-independent sulfate anion transporter SLC26A11 is targeted to the cell membrane and displays Na+-independent sulfate transport activity. SLC26A11 is expressed in kidney, brain and placenta and at lower levels in other tissues (Vincourt et al. 2003).
The sodium-coupled monocarboxylate transporter 2 (SLC5A12, SMCT2) acts as a plasma membrane-bound electroneutral and low-affinity Na+-dependent sodium-coupled solute transporter. It is highly expressed in the kidney cortex and may be responsible for the first step of reabsorption of monocarboxylates from the proximal tubule lumen. Functional studies of SLC5A12 expressed in mammalian cells show it can mediate cotransport of Na+ with lactate, pyruvate and nicotinate (Gopal et al. 2007).
SLC4A family members 4, 5, 7, and 9 can each couple the transport of bicarbonate (HCO3-) with sodium ions (Na+). SLC4A4 (aka NBCE1) is an electrogenic sodium/bicarbonate cotransporter with a Na+:HCO3- stoichiometry of 1:3, although it can also be 1:2 (Burnham et al. 1997). SLC4A4 encodes a protein which is expressed in the kidney and pancreas, with lesser expression in many other tissues (Abuladze et al. 1998). Mutations in SLC4A4 cause permanent isolated proximal renal tubular acidosis (pRTA) (results in accumulation of acid in the body due to a failure of the kidneys to effectively acidify urine) with ocular abnormalities (Igarashi et al. 1999).
Adenosylhomocysteinase 2 (AHCYL2) can upregulate ion-transporting proteins such as the electrogenic sodium bicarbonate cotransporter 1 (SLC4A4, aka NBCE1) (Yamaguchi & Ishikawa 2014).
Members of the solute carrier family 25 (SLC25) can transport carboxylates, amino acids, nucleotides and cofactors across the inner mitochondrial membrane, thereby connecting cytosolic and matrix functions. The main physiological role of mitochondrial basic amino acids transporter (SLC25A29) is to carry basic amino acids into the mitochondrion. It transports arginine (L-Arg), lysine (L-Lys), homoarginine (homoArg), methylarginine (methylArg) and, to a much lesser extent, ornithine (L-Orn) and histidine (L-His) (Porcelli et al. 2014).
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cysteinethreonine, or
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SLC5A8Annotated Interactions
SLC4A1 (Band 3, AE1, anion exchanger 1) was the first bicarbonate transporter gene to be cloned and sequenced (Lux et al. 1989). It is ubiquitous throughout vertebrates and in humans, is present on erythrocytes and the basolateral surfaces of kidney cells. The erythrocyte and kidney forms are different isoforms of the same protein (Kollert-Jons et al. 1993). Variations in erythroid AE1 determine the Diego blood group system (Bruce et al. 1994). A more serious consequence of mutated erythroid AE1 is Hereditary spherocytosis (a disorder leading to haemolytic anaemia) (Jarolim et al. 1995). Defects in the kidney form of AE1 cause distal (type1) renal tubular acidosis (an inability to acidify urine) (Bruce et al. 1997).
SLC4A2 (Non-erythroid band 3-like protein, AE2, anion exchanger 2) is widely expressed and is considered to be the 'housekeeping' isoform of the bicarbonate transporters (Demuth et al. 1986). SLC4A3 (Cardiac/brain band 3-like protein, AE3) is expressed in heart and brain (Yannoukakos et al. 1994).
SLC4A7 (aka NBC3, NBCn1) encodes a protein which performs electroneutral cotransport of Na+ and HCO3- with a 1:1 stoichiometry. It is highly expressed in testes and spleen and, to a lesser extent, in many other tissues including heart, muscle, kidney and GI tract (Pushkin et al. 1999).
SLC4A9 (aka AE4) was originally thought to exchange Cl- with HCO3- (hence the name AE4) but this has not been reported. Consensus has emerged that it is indeed a Na+/HCO3- co-transporter (Lipovich et al. 2001). It is predominantly expressed in the kidney, salivary glands, testes, thyroid glands and trachea (Parker et al. 2001).
In Rabbits, sorcin (SRI) activates SLC8A1, via the interaction of the respective Ca2+-binding domains (Zamparelli et al. 2010). Calmodulin (CALM1) binds to the cytoplasmic loop of NCX1 to negatively regulate exchange activity (Chou et al. 2015).
SLC12A4 encodes KCC1 (Gillen CM et al, 1996). KCC1 is ubiquitously expressed, suggesting a housekeeping role in the regulation of cell volume. SLC12A5 encodes KCC2 (Song L et al, 2002). KCC2's expression is restricted to neurons in the CNS and retina. It is thought KCC2 is important for Cl- homeostasis in neurons. SLC12A6 encodes KCC3 (Race JE et al, 1999; Mount DB et al, 1999). KCC3 is highly expressed in heart, brain, spinal cord, kidney, muscle, pancreas and placenta. Defects in SLC12A6 are a cause of agenesis of the corpus callosum with peripheral neuropathy (ACCPN) (Howard HC et al, 2002). SLC12A7 encodes KCC4 (Mount DB et al, 1999) which is widely expressed, especially in the kidney. It is thought to play a role in transepithelial transport of Cl- by the proximal tubule.
Defects in SLC34A1 are the cause of hypophosphatemic nephrolithiasis/osteoporosis type 1 (NPHLOP1) (Prie et al. 2002). Defects in SLC34A2 are a cause of pulmonary alveolar microlithiasis, a rare disease characterised by the deposition of calcium phosphate microliths throughout the lung (Corut et al. 2006).
SLC26A3 (Chloride anion exchanger, Down-regulated in adenoma, DRA) is expressed in the mucosa of the colon and helps mediate electrolyte and fluid absorption (Schweinfest et al. 1993). Defects in SLC26A3 cause congenital chloride diarrhea 1 (DIAR1), a disease characterized by watery stools containing an excess of chloride (Hoeglund et al. 1996). SLC26A6 encodes a protein involved in transporting chloride, oxalate, sulfate and bicarbonate (Waldegger et al. 2001). It is ubiquitously expressed, the highest levels present in kidney and pancreas.
The SLC1 gene family includes five high-affinity glutamate transporters encoded by SLC1, 2, 3, 6 and 7. These transporters can mediate transport of L-Glutamate, L-Aspartate and D-Aspartate with cotransport of 3 Na+ ions and H+ and antiport of a K+ ion. This mechanism allows glutamate into cells against a concentration gradient. This is a crucial factor in the protection of neurons against glutamate excitotoxicity in the CNS.
SLC1A1 encodes an excitatory amino-acid carrier 1 (EAAC1, also called EAAT3) (Shashidharan et al. 1994, Arriza et al. 1994) and is abundant particularly in brain but also in liver, muscle, ovary, testis and in retinoblastoma cell lines. In the kidney, EAAC1 is present at apical membranes of proximal tubes. Defects in SLC1A1 are the cause of dicarboxylic aminoaciduria (glutamate-aspartate transport defect in the kidney and intestine). SLC1A2 encodes the glial-type high affinity glutamate transporter (GLT1, EAAT2) (Arriza et al. 1994). GLT1 is expressed mainly in the brain and is essential for terminating the postsynaptic action of glutamate by rapidly removing released glutamate from the synaptic cleft.
SLC1A3 encodes a sodium-dependent glutamate/aspartate transporter 1 (GLAST1, EAAT1). It is particularly abundant in the cerebellum and, like GLT1, plays a role in terminating the postsynaptic action of glutamate (Arriza JL et al, 1994). Defects in SLC1A3 are the cause of episodic ataxia type 6 (EA6), characterized by episodic ataxia, seizures, migraine and alternating hemiplegia (Jen JC et al, 2005).
SLC1A6 encodes an excitatory amino-acid transporter 4 (EAAT4) (Fairman WA et al, 1995) and is predominantly expressed in cerebellar Purkinje cells. SLC1A7 encodes an excitatory amino acid transporter 5 (EAAT5, retinal glutamate transporter) (Arriza JL et al, 1997) which is highly expressed in the retina.
Three members of the SLC17A gene family (7, 6 and 8) encode VGLUTs 1-3 respectively (Ni et al. 1996, Takamori et al. 2001, Takamori et al. 2002 respectively). VGLUT1 (brain-specific Na+-dependent phopshate transporter, BNPI) and VGLUT2 (differentiation-associated Na+-dependent phosphate transporter, DNPI) were identified first and originally characterized as phosphate transporters. However, they are localized to synaptic vesicles, not the plasma membrane (like EAATs) and transport the organic anion glutamate into synaptic vesicles. This uptake is thought to be coupled to the proton electrochemical gradient generated by a vacuolar type H+-ATPase. They are all expressed in the CNS in neuron-rich areas but VGLUT3 is also expressed on astrocytes and in liver and kidney.
Three close relatives of NPT1 have been identified through genomic analysis and designated NPT3 (SLC17A2), NPT4 (SLC17A3) and a putative small intestine sodium-dependent phosphate co-transporter (SLC17A4). None of these three proteins have been functionally characterized yet.
transmitter of the vertebrate retina. The gene SLC32A1 encodes the vesicular inhibitory amino acid transporter (VIAAT, also called vesicular GABA transporter VGAT) (Jellali A et al, 2002). VIAAT is a proton-coupled amino acid antiporter, uptaking the inhibitory neurotransmitters GABA and glycine into synaptic vesicles in exchange for protons. This process is driven by the H+-ATPase, providing the driving force for uptake of these neurotransmitters. The protein is expressed throughout the terminal ends of horizontal cells of the retina.
Adenosylhomocysteinase 2 (AHCYL2) can upregulate ion-transporting proteins such as the electrogenic sodium bicarbonate cotransporter 1 (SLC4A4, aka NBCE1) (Yamaguchi & Ishikawa 2014).
threonine, or
cysteinethreonine, or
cysteinethreonine, or
cysteinethreonine, or
cysteinethreonine, or
cysteinethreonine, or
cysteinethreonine, or
cysteinethreonine, or
cysteinetransported by
SLC5A8transported by
SLC5A8