Abacavir transport and metabolism (Homo sapiens)
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Description
Abacavir is a nucleoside analogue reverse transcriptase inhibitor with antiretroviral activity, widely used in combination with other drugs to treat HIV-1 infection (Yuen et al. 2008). Its uptake across the plasma membrane is mediated by organic cation transporters SLC22A1, 2, and 3; the transport proteins ABCB1 and ABCG2 mediate its efflux. Abacavir itself is a prodrug. Activation requires phosphorylation by a cytosolic adenosine phosphotransferase and deamination by ADAL deaminase to yield carbovir monophosphate. Cytosolic nucleotide kinases convert carbovir monophosphate to carbovir triphosphate, the active HIV reverse transcriptase inhibitor. Abacavir can be glucuronidated or oxidized to a 5'-carboxylate; these are the major forms in which it is excreted from the body.
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- Spychała J, Madrid-Marina V, Fox IH.; ''High Km soluble 5'-nucleotidase from human placenta. Properties and allosteric regulation by IMP and ATP.''; PubMed Europe PMC Scholia
- Garvey EP, Krenitsky TA.; ''A novel human phosphotransferase highly specific for adenosine.''; PubMed Europe PMC Scholia
- McDowell JA, Chittick GE, Ravitch JR, Polk RE, Kerkering TM, Stein DS.; ''Pharmacokinetics of [(14)C]abacavir, a human immunodeficiency virus type 1 (HIV-1) reverse transcriptase inhibitor, administered in a single oral dose to HIV-1-infected adults: a mass balance study.''; PubMed Europe PMC Scholia
- Johnson MA, Fridland A.; ''Phosphorylation of 2',3'-dideoxyinosine by cytosolic 5'-nucleotidase of human lymphoid cells.''; PubMed Europe PMC Scholia
- Miller WH, Daluge SM, Garvey EP, Hopkins S, Reardon JE, Boyd FL, Miller RL.; ''Phosphorylation of carbovir enantiomers by cellular enzymes determines the stereoselectivity of antiviral activity.''; PubMed Europe PMC Scholia
- Yuen GJ, Weller S, Pakes GE.; ''A review of the pharmacokinetics of abacavir.''; PubMed Europe PMC Scholia
- Wakabayashi K, Nakagawa H, Tamura A, Koshiba S, Hoshijima K, Komada M, Ishikawa T.; ''Intramolecular disulfide bond is a critical check point determining degradative fates of ATP-binding cassette (ABC) transporter ABCG2 protein.''; PubMed Europe PMC Scholia
- Yin SJ, Bosron WF, Magnes LJ, Li TK.; ''Human liver alcohol dehydrogenase: purification and kinetic characterization of the beta 2 beta 2, beta 2 beta 1, alpha beta 2, and beta 2 gamma 1 "Oriental" isoenzymes.''; PubMed Europe PMC Scholia
- Pan G, Giri N, Elmquist WF.; ''Abcg2/Bcrp1 mediates the polarized transport of antiretroviral nucleosides abacavir and zidovudine.''; PubMed Europe PMC Scholia
- Minuesa G, Volk C, Molina-Arcas M, Gorboulev V, Erkizia I, Arndt P, Clotet B, Pastor-Anglada M, Koepsell H, Martinez-Picado J.; ''Transport of lamivudine [(-)-beta-L-2',3'-dideoxy-3'-thiacytidine] and high-affinity interaction of nucleoside reverse transcriptase inhibitors with human organic cation transporters 1, 2, and 3.''; PubMed Europe PMC Scholia
- Shaik N, Giri N, Pan G, Elmquist WF.; ''P-glycoprotein-mediated active efflux of the anti-HIV1 nucleoside abacavir limits cellular accumulation and brain distribution.''; PubMed Europe PMC Scholia
- Faletto MB, Miller WH, Garvey EP, St Clair MH, Daluge SM, Good SS.; ''Unique intracellular activation of the potent anti-human immunodeficiency virus agent 1592U89.''; PubMed Europe PMC Scholia
- Lange LG, Sytkowski AJ, Vallee BL.; ''Human liver alcohol dehydrogenase: purification, composition, and catalytic features.''; PubMed Europe PMC Scholia
- Klaassen CD, Aleksunes LM.; ''Xenobiotic, bile acid, and cholesterol transporters: function and regulation.''; PubMed Europe PMC Scholia
- Ravitch JR, Moseley CG.; ''High-performance liquid chromatographic assay for abacavir and its two major metabolites in human urine and cerebrospinal fluid.''; PubMed Europe PMC Scholia
- Murakami E, Bao H, Mosley RT, Du J, Sofia MJ, Furman PA.; ''Adenosine deaminase-like protein 1 (ADAL1): characterization and substrate specificity in the hydrolysis of N(6)- or O(6)-substituted purine or 2-aminopurine nucleoside monophosphates.''; PubMed Europe PMC Scholia
- Walldén K, Stenmark P, Nyman T, Flodin S, Gräslund S, Loppnau P, Bianchi V, Nordlund P.; ''Crystal structure of human cytosolic 5'-nucleotidase II: insights into allosteric regulation and substrate recognition.''; PubMed Europe PMC Scholia
- Doyle LA, Yang W, Abruzzo LV, Krogmann T, Gao Y, Rishi AK, Ross DD.; ''A multidrug resistance transporter from human MCF-7 breast cancer cells.''; PubMed Europe PMC Scholia
- Walsh JS, Reese MJ, Thurmond LM.; ''The metabolic activation of abacavir by human liver cytosol and expressed human alcohol dehydrogenase isozymes.''; PubMed Europe PMC Scholia
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Annotated Interactions
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| Source | Target | Type | Database reference | Comment |
|---|---|---|---|---|
| ABCB1 | mim-catalysis | R-HSA-2161538 (Reactome)  | ||
| ABCG2 dimer | mim-catalysis | R-HSA-2161506 (Reactome) | ||
| ADAL:Zn | mim-catalysis | R-HSA-2161195 (Reactome) | ||
| ADH1A:2Zn2+ dimer | mim-catalysis | R-HSA-2162078 (Reactome) | ||
| ADP | Arrow | R-HSA-2161506 (Reactome) | ||
| ADP | Arrow | R-HSA-2161538 (Reactome) | ||
| ADP | Arrow | R-HSA-2162092 (Reactome) | ||
| ADP | Arrow | R-HSA-2162096 (Reactome) | ||
| AMP | R-HSA-2161193 (Reactome) | |||
| ATP | R-HSA-2161506 (Reactome) | |||
| ATP | R-HSA-2161538 (Reactome) | |||
| ATP | R-HSA-2162092 (Reactome) | |||
| ATP | R-HSA-2162096 (Reactome) | |||
| Ade-Rib | Arrow | R-HSA-2161193 (Reactome) | ||
| GUK1 | mim-catalysis | R-HSA-2162092 (Reactome) | ||
| H+ | Arrow | R-HSA-2162078 (Reactome) | ||
| H2O | R-HSA-2161195 (Reactome) | |||
| H2O | R-HSA-2161506 (Reactome) | |||
| H2O | R-HSA-2161538 (Reactome) | |||
| IMP | R-HSA-2162066 (Reactome) | |||
| Ino | Arrow | R-HSA-2162066 (Reactome) | ||
| NAD+ | R-HSA-2162078 (Reactome) | |||
| NADH | Arrow | R-HSA-2162078 (Reactome) | ||
| NT5C2 tetramer | mim-catalysis | R-HSA-2162066 (Reactome) | ||
| PCK1 | mim-catalysis | R-HSA-2162096 (Reactome) | ||
| Pi | Arrow | R-HSA-2161506 (Reactome) | ||
| Pi | Arrow | R-HSA-2161538 (Reactome) | ||
| R-HSA-2161193 (Reactome) | Cytosolic adenosine phosphotransferase catalyzes the reaction of abacavir and AMP to form abacavir monophosphate and adenosine (Faletto et al. 1997). This enzymatic activity has been purified from human placenta and is distinct from known human kinases (Garvey and Krenitsky 1992) but has not been associated with a known human gene. | |||
| R-HSA-2161195 (Reactome) | Cytosolic ADAL (Adenosine DeAminase-Like) catalyzes the reaction of abacavir monophosphate and water to form carbovir monophosphate and cyclopropylamine. The active form of the enzyme is a protein monomer complexed with a zinc ion (Murakami et al. 2011). | |||
| R-HSA-2161500 (Reactome) | Organic cation transporters 1 (OCT1, SLC22A1), 2 (OCT2, SLC22A2) and 3 (OCT3, SLC22A3) associated with the plasma membrane all mediate the influx of abacavir. The three transporters have similar affinities for abacavir (Minuesa et al. 2009) but differ in the tissues in which they are expressed and in their distributions on the surfaces of polarized cells (reviewed by Klaasen and Aleksunes 2010). | |||
| R-HSA-2161506 (Reactome) | ATP-binding cassette sub-family G member 2 (ABCG2), associated with the plasma membrane, mediates the ATP-dependent efflux of abacavir (Doyle et al. 1998). The active form of ABCG2 is a homodimer stabilized by an interchain disulfide bond (Wakabayashi et al. 2007). The abacavir specificity of the human ABCG2 transporter is inferred from studies of the corresponding mouse protein (Pan et al. 2007). | |||
| R-HSA-2161538 (Reactome) | The ABCB1 transporter associated with the plasma membrane mediates the ATP-dependent efflux of a variety of xenobiotic molecules. Its ability to transport abacavir is inferred from studies of the corresponding mouse protein (Shaik et al. 2007). | |||
| R-HSA-2162066 (Reactome) | NT5C2 catalyzes the reaction of carbovir and IMP to form carbovir monophosphate and inosine (Johnson and Fridland 1989; Miller et al. 1992). The enzyme was originally identified as a high-Km soluble 5'-nucleotidase most active on IMP and GMP (Spychala et al. 1988). Its active form is a tetramer (Wallden et al. 2007). | |||
| R-HSA-2162078 (Reactome) | Cytosolic ADH alpha dimer catalyzes the reaction of abacavir and NAD to form abacavir 5'-carboxylate and NADH + H+. Abacavir 5'-carboxylate is one of the major forms in which abacavir is excreted from the body. Studies with purified enzymes in vitro indicate that only the alpha isoform of ADH has this activity. These studies also suggest that the reaction proceeds in two steps via an unstable aldehyde intermediate (Walsh et al. 2002). Whether conversion of the aldehyde to the carboxylate is spontaneous or also catalyzed by ADH has not been established. | |||
| R-HSA-2162092 (Reactome) | Cytosolic GUK1 (guanylate kinase 1) catalyzes the reaction of carbovir monophosphate and ATP to form carbovir diphosphate and ADP. The activity of human GUK1 is inferred from that of the corresponding pig protein (Miller et al. 1992). | |||
| R-HSA-2162096 (Reactome) | Cytosolic PCK1 (phosphoenolpyruvate carboxykinase 1) catalyzes the reaction of carbovir diphosphate and ATP to form carbovir triphosphate and ADP. The activity of human PCK1 and relative inactivity of human nucleoside diphosphate kinase are inferred from the properties of the purified rat and bovine enzymes in vitro (Miller et al. 1992). | |||
| R-HSA-2162099 (Reactome) | A member of the UDPGT (UDP-glucuronosyltransferase) enzyme family is thought to catalyze the reaction of abacavir and UDP-glucuronate to form UDP and abacavir-5'-glucuronate, one of the major forms in which abacavir is excreted from the body (McDowell et al. 1999; Ravitch and Moseley 2001). The specific UDPGT family enzyme family member or members that catalyze this reaction have not been identified. | |||
| SLC22A1,2,3 | mim-catalysis | R-HSA-2161500 (Reactome) | ||
| UDP-GlcA | R-HSA-2162099 (Reactome) | |||
| UDP | Arrow | R-HSA-2162099 (Reactome) | ||
| UDPGT | mim-catalysis | R-HSA-2162099 (Reactome) | ||
| abacavir 5'-carboxylic acid | Arrow | R-HSA-2162078 (Reactome) | ||
| abacavir 5'-glucuronide | Arrow | R-HSA-2162099 (Reactome) | ||
| abacavir monophosphate | Arrow | R-HSA-2161193 (Reactome) | ||
| abacavir monophosphate | R-HSA-2161195 (Reactome) | |||
| abacavir | Arrow | R-HSA-2161500 (Reactome) | ||
| abacavir | Arrow | R-HSA-2161506 (Reactome) | ||
| abacavir | Arrow | R-HSA-2161538 (Reactome) | ||
| abacavir | R-HSA-2161193 (Reactome) | |||
| abacavir | R-HSA-2161500 (Reactome) | |||
| abacavir | R-HSA-2161506 (Reactome) | |||
| abacavir | R-HSA-2161538 (Reactome) | |||
| abacavir | R-HSA-2162078 (Reactome) | |||
| abacavir | R-HSA-2162099 (Reactome) | |||
| adenosine phosphotransferase | mim-catalysis | R-HSA-2161193 (Reactome) | ||
| carbovir monophosphate | Arrow | R-HSA-2161195 (Reactome) | ||
| carbovir monophosphate | Arrow | R-HSA-2162066 (Reactome) | ||
| carbovir monophosphate | R-HSA-2162092 (Reactome) | |||
| carbovir triphosphate | Arrow | R-HSA-2162096 (Reactome) | ||
| carbovir diphosphate | Arrow | R-HSA-2162092 (Reactome) | ||
| carbovir diphosphate | R-HSA-2162096 (Reactome) | |||
| carbovir | R-HSA-2162066 (Reactome) | |||
| cyclopropylamine | Arrow | R-HSA-2161195 (Reactome) |
