Insulin binding to its receptor results in receptor autophosphorylation on tyrosine residues and the tyrosine phosphorylation of insulin receptor substrates (e.g. IRS and Shc) by the insulin receptor tyrosine kinase. This allows association of IRSs with downstream effectors such as PI-3K via its Src homology 2 (SH2) domains leading to end point events such as Glut4 (Slc2a4) translocation. Shc when tyrosine phosphorylated associates with Grb2 and can thus activate the Ras/MAPK pathway independent of the IRSs.
Signal transduction by the insulin receptor is not limited to its activation at the cell surface. The activated ligand-receptor complex initially at the cell surface, is internalised into endosomes itself a process which is dependent on tyrosine autophosphorylation. Endocytosis of activated receptors has the dual effect of concentrating receptors within endosomes and allows the insulin receptor tyrosine kinase to phosphorylate substrates that are spatially distinct from those accessible at the plasma membrane. Acidification of the endosomal lumen, due to the presence of proton pumps, results in dissociation of insulin from its receptor. (The endosome constitutes the major site of insulin degradation). This loss of the ligand-receptor complex attenuates any further insulin-driven receptor re-phosphorylation events and leads to receptor dephosphorylation by extra-lumenal endosomally-associated protein tyrosine phosphatases (PTPs). The identity of these PTPs is not clearly established yet.
View original pathway at Reactome.</div>
Boriack-Sjodin PA, Margarit SM, Bar-Sagi D, Kuriyan J.; ''The structural basis of the activation of Ras by Sos.''; PubMedEurope PMCScholia
Cseh B, Doma E, Baccarini M.; ''"RAF" neighborhood: protein-protein interaction in the Raf/Mek/Erk pathway.''; PubMedEurope PMCScholia
Wick KR, Werner ED, Langlais P, Ramos FJ, Dong LQ, Shoelson SE, Liu F.; ''Grb10 inhibits insulin-stimulated insulin receptor substrate (IRS)-phosphatidylinositol 3-kinase/Akt signaling pathway by disrupting the association of IRS-1/IRS-2 with the insulin receptor.''; PubMedEurope PMCScholia
Bouzakri K, Zachrisson A, Al-Khalili L, Zhang BB, Koistinen HA, Krook A, Zierath JR.; ''siRNA-based gene silencing reveals specialized roles of IRS-1/Akt2 and IRS-2/Akt1 in glucose and lipid metabolism in human skeletal muscle.''; PubMedEurope PMCScholia
Brown MD, Sacks DB.; ''Protein scaffolds in MAP kinase signalling.''; PubMedEurope PMCScholia
Tavaré JM, Denton RM.; ''Studies on the autophosphorylation of the insulin receptor from human placenta. Analysis of the sites phosphorylated by two-dimensional peptide mapping.''; PubMedEurope PMCScholia
Cheatham B, Kahn CR.; ''Insulin action and the insulin signaling network.''; PubMedEurope PMCScholia
Okada S, Pessin JE.; ''Interactions between Src homology (SH) 2/SH3 adapter proteins and the guanylnucleotide exchange factor SOS are differentially regulated by insulin and epidermal growth factor.''; PubMedEurope PMCScholia
Duckworth WC.; ''Insulin degradation: mechanisms, products, and significance.''; PubMedEurope PMCScholia
Drake PG, Posner BI.; ''Insulin receptor-associated protein tyrosine phosphatase(s): role in insulin action.''; PubMedEurope PMCScholia
Turjanski AG, Vaqué JP, Gutkind JS.; ''MAP kinases and the control of nuclear events.''; PubMedEurope PMCScholia
Kleiman LB, Maiwald T, Conzelmann H, Lauffenburger DA, Sorger PK.; ''Rapid phospho-turnover by receptor tyrosine kinases impacts downstream signaling and drug binding.''; PubMedEurope PMCScholia
Waters SB, Yamauchi K, Pessin JE.; ''Insulin-stimulated disassociation of the SOS-Grb2 complex.''; PubMedEurope PMCScholia
Kim B, Cheng HL, Margolis B, Feldman EL.; ''Insulin receptor substrate 2 and Shc play different roles in insulin-like growth factor I signaling.''; PubMedEurope PMCScholia
Zoncu R, Efeyan A, Sabatini DM.; ''mTOR: from growth signal integration to cancer, diabetes and ageing.''; PubMedEurope PMCScholia
Di Guglielmo GM, Drake PG, Baass PC, Authier F, Posner BI, Bergeron JJ.; ''Insulin receptor internalization and signalling.''; PubMedEurope PMCScholia
Skolnik EY, Batzer A, Li N, Lee CH, Lowenstein E, Mohammadi M, Margolis B, Schlessinger J.; ''The function of GRB2 in linking the insulin receptor to Ras signaling pathways.''; PubMedEurope PMCScholia
Chardin P, Camonis JH, Gale NW, van Aelst L, Schlessinger J, Wigler MH, Bar-Sagi D.; ''Human Sos1: a guanine nucleotide exchange factor for Ras that binds to GRB2.''; PubMedEurope PMCScholia
Bevan AP, Drake PG, Bergeron JJ, Posner BI.; ''Intracellular signal transduction: The role of endosomes.''; PubMedEurope PMCScholia
Davies H, Bignell GR, Cox C, Stephens P, Edkins S, Clegg S, Teague J, Woffendin H, Garnett MJ, Bottomley W, Davis N, Dicks E, Ewing R, Floyd Y, Gray K, Hall S, Hawes R, Hughes J, Kosmidou V, Menzies A, Mould C, Parker A, Stevens C, Watt S, Hooper S, Wilson R, Jayatilake H, Gusterson BA, Cooper C, Shipley J, Hargrave D, Pritchard-Jones K, Maitland N, Chenevix-Trench G, Riggins GJ, Bigner DD, Palmieri G, Cossu A, Flanagan A, Nicholson A, Ho JW, Leung SY, Yuen ST, Weber BL, Seigler HF, Darrow TL, Paterson H, Marais R, Marshall CJ, Wooster R, Stratton MR, Futreal PA.; ''Mutations of the BRAF gene in human cancer.''; PubMedEurope PMCScholia
Fukumoto T, Kubota Y, Kitanaka A, Yamaoka G, Ohara-Waki F, Imataki O, Ohnishi H, Ishida T, Tanaka T.; ''Gab1 transduces PI3K-mediated erythropoietin signals to the Erk pathway and regulates erythropoietin-dependent proliferation and survival of erythroid cells.''; PubMedEurope PMCScholia
Li N, Batzer A, Daly R, Yajnik V, Skolnik E, Chardin P, Bar-Sagi D, Margolis B, Schlessinger J.; ''Guanine-nucleotide-releasing factor hSos1 binds to Grb2 and links receptor tyrosine kinases to Ras signalling.''; PubMedEurope PMCScholia
Duan C, Li M, Rui L.; ''SH2-B promotes insulin receptor substrate 1 (IRS1)- and IRS2-mediated activation of the phosphatidylinositol 3-kinase pathway in response to leptin.''; PubMedEurope PMCScholia
Kyriakis JM, Avruch J.; ''Mammalian MAPK signal transduction pathways activated by stress and inflammation: a 10-year update.''; PubMedEurope PMCScholia
Liu YF, Paz K, Herschkovitz A, Alt A, Tennenbaum T, Sampson SR, Ohba M, Kuroki T, LeRoith D, Zick Y.; ''Insulin stimulates PKCzeta -mediated phosphorylation of insulin receptor substrate-1 (IRS-1). A self-attenuated mechanism to negatively regulate the function of IRS proteins.''; PubMedEurope PMCScholia
Qin A, Cheng TS, Lin Z, Pavlos NJ, Jiang Q, Xu J, Dai KR, Zheng MH.; ''Versatile roles of V-ATPases accessory subunit Ac45 in osteoclast formation and function.''; PubMedEurope PMCScholia
Ullrich A, Bell JR, Chen EY, Herrera R, Petruzzelli LM, Dull TJ, Gray A, Coussens L, Liao YC, Tsubokawa M.; ''Human insulin receptor and its relationship to the tyrosine kinase family of oncogenes.''; PubMedEurope PMCScholia
Roskoski R.; ''MEK1/2 dual-specificity protein kinases: structure and regulation.''; PubMedEurope PMCScholia
Supek F, Supekova L, Mandiyan S, Pan YC, Nelson H, Nelson N.; ''A novel accessory subunit for vacuolar H(+)-ATPase from chromaffin granules.''; PubMedEurope PMCScholia
Takahashi Y, Tobe K, Kadowaki H, Katsumata D, Fukushima Y, Yazaki Y, Akanuma Y, Kadowaki T.; ''Roles of insulin receptor substrate-1 and Shc on insulin-like growth factor I receptor signaling in early passages of cultured human fibroblasts.''; PubMedEurope PMCScholia
Roskoski R.; ''RAF protein-serine/threonine kinases: structure and regulation.''; PubMedEurope PMCScholia
Van Obberghen E, Baron V, Delahaye L, Emanuelli B, Filippa N, Giorgetti-Peraldi S, Lebrun P, Mothe-Satney I, Peraldi P, Rocchi S, Sawka-Verhelle D, Tartare-Deckert S, Giudicelli J.; ''Surfing the insulin signaling web.''; PubMedEurope PMCScholia
Ebina Y, Ellis L, Jarnagin K, Edery M, Graf L, Clauser E, Ou JH, Masiarz F, Kan YW, Goldfine ID.; ''The human insulin receptor cDNA: the structural basis for hormone-activated transmembrane signalling.''; PubMedEurope PMCScholia
McKay MM, Morrison DK.; ''Integrating signals from RTKs to ERK/MAPK.''; PubMedEurope PMCScholia
White MF.; ''The IRS-signalling system: a network of docking proteins that mediate insulin action.''; PubMedEurope PMCScholia
Ravichandran LV, Esposito DL, Chen J, Quon MJ.; ''Protein kinase C-zeta phosphorylates insulin receptor substrate-1 and impairs its ability to activate phosphatidylinositol 3-kinase in response to insulin.''; PubMedEurope PMCScholia
Sasaoka T, Kobayashi M.; ''The functional significance of Shc in insulin signaling as a substrate of the insulin receptor.''; PubMedEurope PMCScholia
Bergeron JJ, Cruz J, Khan MN, Posner BI.; ''Uptake of insulin and other ligands into receptor-rich endocytic components of target cells: the endosomal apparatus.''; PubMedEurope PMCScholia
Langlais P, Dong LQ, Ramos FJ, Hu D, Li Y, Quon MJ, Liu F.; ''Negative regulation of insulin-stimulated mitogen-activated protein kinase signaling by Grb10.''; PubMedEurope PMCScholia
Kim B, Leventhal PS, White MF, Feldman EL.; ''Differential regulation of insulin receptor substrate-2 and mitogen-activated protein kinase tyrosine phosphorylation by phosphatidylinositol 3-kinase inhibitors in SH-SY5Y human neuroblastoma cells.''; PubMedEurope PMCScholia
Roberts PJ, Der CJ.; ''Targeting the Raf-MEK-ERK mitogen-activated protein kinase cascade for the treatment of cancer.''; PubMedEurope PMCScholia
Corbalan-Garcia S, Yang SS, Degenhardt KR, Bar-Sagi D.; ''Identification of the mitogen-activated protein kinase phosphorylation sites on human Sos1 that regulate interaction with Grb2.''; PubMedEurope PMCScholia
Xu B, Bird VG, Miller WT.; ''Substrate specificities of the insulin and insulin-like growth factor 1 receptor tyrosine kinase catalytic domains.''; PubMedEurope PMCScholia
Gu J, Tamura M, Pankov R, Danen EH, Takino T, Matsumoto K, Yamada KM.; ''Shc and FAK differentially regulate cell motility and directionality modulated by PTEN.''; PubMedEurope PMCScholia
Ward CW, Gough KH, Rashke M, Wan SS, Tribbick G, Wang J.; ''Systematic mapping of potential binding sites for Shc and Grb2 SH2 domains on insulin receptor substrate-1 and the receptors for insulin, epidermal growth factor, platelet-derived growth factor, and fibroblast growth factor.''; PubMedEurope PMCScholia
Cargnello M, Roux PP.; ''Activation and function of the MAPKs and their substrates, the MAPK-activated protein kinases.''; PubMedEurope PMCScholia
Sasaoka T, Ishihara H, Sawa T, Ishiki M, Morioka H, Imamura T, Usui I, Takata Y, Kobayashi M.; ''Functional importance of amino-terminal domain of Shc for interaction with insulin and epidermal growth factor receptors in phosphorylation-independent manner.''; PubMedEurope PMCScholia
The human insulin receptor is expressed as two isoforms that are generated by alternate splicing of its mRNA; the B isoform has 12 additional amino acids (718-729) encoded by exon 11 of the gene.
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.
Target of rapamycin (mTOR) is a highly-conserved serine/threonine kinase that regulates cell growth and division in response to energy levels, growth signals, and nutrients (Zoncu et al. 2011). Control of mTOR activity is critical for the cell since its dysregulation leads to cancer, metabolic disease, and diabetes (Laplante & Sabatini 2012). In cells, mTOR exists as two structurally distinct complexes termed mTOR complex 1 (mTORC1) and mTOR complex 2 (mTORC2), each one with specificity for different sets of effectors. mTORC1 couples energy and nutrient abundance to cell growth and proliferation by balancing anabolic (protein synthesis and nutrient storage) and catabolic (autophagy and utilization of energy stores) processes.
The RAS-RAF-MEK-ERK pathway regulates processes such as proliferation, differentiation, survival, senescence and cell motility in response to growth factors, hormones and cytokines, among others. Binding of these stimuli to receptors in the plasma membrane promotes the GEF-mediated activation of RAS at the plasma membrane and initiates the three-tiered kinase cascade of the conventional MAPK cascades. GTP-bound RAS recruits RAF (the MAPK kinase kinase), and promotes its dimerization and activation (reviewed in Cseh et al, 2014; Roskoski, 2010; McKay and Morrison, 2007; Wellbrock et al, 2004). Activated RAF phosphorylates the MAPK kinase proteins MEK1 and MEK2 (also known as MAP2K1 and MAP2K2), which in turn phophorylate the proline-directed kinases ERK1 and 2 (also known as MAPK3 and MAPK1) (reviewed in Roskoski, 2012a, b; Kryiakis and Avruch, 2012). Activated ERK proteins may undergo dimerization and have identified targets in both the nucleus and the cytosol; consistent with this, a proportion of activated ERK protein relocalizes to the nucleus in response to stimuli (reviewed in Roskoski 2012b; Turjanski et al, 2007; Plotnikov et al, 2010; Cargnello et al, 2011). Although initially seen as a linear cascade originating at the plasma membrane and culminating in the nucleus, the RAS/RAF MAPK cascade is now also known to be activated from various intracellular location. Temporal and spatial specificity of the cascade is achieved in part through the interaction of pathway components with numerous scaffolding proteins (reviewed in McKay and Morrison, 2007; Brown and Sacks, 2009). The importance of the RAS/RAF MAPK cascade is highlighted by the fact that components of this pathway are mutated with high frequency in a large number of human cancers. Activating mutations in RAS are found in approximately one third of human cancers, while ~8% of tumors express an activated form of BRAF (Roberts and Der, 2007; Davies et al, 2002; Cantwell-Dorris et al, 2011).
SOS promotes the formation of GTP-bound RAS, thus activating this protein. RAS activation results in activation of the protein kinases RAF1, B-Raf, and MAP-ERK kinase kinase (MEKK), and the catalytic subunit of PI3K, as well as of a series of RALGEFs. The activation cycle of RAS GTPases is regulated by their interaction with specific guanine nucleotide exchange factors (GEFs) and GTPase-activating proteins (GAPs). GEFs promote activation by inducing the release of GDP, whereas GAPs inactivate RAS-like proteins by stimulating their intrinsic GTPase activity. NGF-induced RAS activation via SHC-GRB2-SOS is maximal at 2 min but it is no longer detected after 5 min. Therefore, the transient activation of RAS obtained through SHC-GRB2-SOS is insufficient for the prolonged activation of ERKs found in NGF-treated cells.
In the cytoplasm of unstimulated cells, SOS1 is found in a complex with GRB2. The interaction occurs between the carboxy terminal domain of SOS1 and the Src homology 3 (SH3) domains of GRB2.
SOS promotes the formation of GTP-bound RAS, thus activating this protein. RAS activation results in activation of the protein kinases RAF1, B-Raf, and MAP-ERK kinase kinase (MEKK), and the catalytic subunit of PI3K, as well as of a series of RALGEFs. The activation cycle of RAS GTPases is regulated by their interaction with specific guanine nucleotide exchange factors (GEFs) and GTPase-activating proteins (GAPs). GEFs promote activation by inducing the release of GDP, whereas GAPs inactivate RAS-like proteins by stimulating their intrinsic GTPase activity. NGF-induced RAS activation via SHC-GRB2-SOS is maximal at 2 min but it is no longer detected after 5 min. Therefore, the transient activation of RAS obtained through SHC-GRB2-SOS is insufficient for the prolonged activation of ERKs found in NGF-treated cells.
At the beginning of this reaction, 1 molecule of 'ATP', and 1 molecule of 'GRB2:SOS:SHC-P' are present. At the end of this reaction, 1 molecule of 'GRB2:SHC-P', 1 molecule of 'phospho-SOS', and 1 molecule of 'ADP' are present.
At the beginning of this reaction, 4 molecules of 'ATP', and 1 molecule of 'GRB2:SOS:IRS-P' are present. At the end of this reaction, 1 molecule of 'GRB2:IRS-P', 1 molecule of 'phospho-SOS', and 4 molecules of 'ADP' are present.
This reaction takes place on the 'internal side of plasma membrane' and is mediated by the 'kinase activity' of 'ERK1'.
Grb10 negatively regulates the insulin-dependent phosphatidylinositol 3-kinase/Akt signaling pathway by disrupting the association of IRS-1/IRS-2 with the insulin receptor (Wick et al, 2003;Langlais et al, 2004).
Vacuolar-type H+-ATPases (V-ATPases) are proton pumps that acidify intracellular cargos and deliver protons across the plasma membrane of many specialised cells. V-type proton ATPase subunit S1 (ATP6AP1) is thought to function as an accessory subunit of the V0 subcomplex of V-ATPase, facilitating acidification (Supek et al. 1994). Experiments with the mouse orthologue reveals a role for Atp6ap1 in osteoclast formation and function (Qin et al. 2011).
Using receptor mutagenesis studies it is known that IRS1 via its PTB domain binds to the insulin receptor at the juxtamembrane region at tyrosine 972. The interaction is further stabilized by the PH domain of IRS1 which interacts with the phospholipids of the plasma membrane. This allows the receptor to phosphorylate IRS1 on up to 13 of its tyrosine residues (Tavare and Denton 1998, Duan et al.2004).
At the beginning of this reaction, 1 molecule of 'ATP', and 1 molecule of 'IRS:activated insulin receptor' are present. At the end of this reaction, 1 molecule of 'phospho-IRS:activated insulin receptor', and 1 molecule of 'ADP' are present.
This reaction takes place on the 'internal side of plasma membrane' and is mediated by the 'transmembrane receptor protein tyrosine kinase activity' of 'IRS:activated insulin receptor'.
At the beginning of this reaction, 1 molecule of 'phospho-IRS:activated insulin receptor' is present. At the end of this reaction, 1 molecule of 'activated insulin receptor', and 1 molecule of 'phospho-IRS' are present.
This reaction takes place on the 'internal side of plasma membrane'.
In Fao or NIH3T3 cells stably expressing IR, overexpression of PKCζ enhances the dissociation from IR and decrease in IRS1 tyrosine phosphorylation caused by prolonged insulin stimulation (Riu et al. 2001, Ravichandran et al. 2001).
Under normal physiological conditions blood glucose levels are kept under tight control by a series of regulated steps that ensure glucose homeostasis. Upon feeding glucose levels rise and in response to this the body secretes insulin from pancreatic beta-cells into the blood. At physiological concentrations insulin is present in the blood in its monomeric form. The insulin receptor is a tetramer, consisting of two alpha and two beta chains, which are produced by cleavage of a single translated peptide chain (Schenker & Kohanski 1991). Binding of insulin to its receptor occurs on the receptor alpha-subunits. There are two binding domains involved on the receptor (L1 and L2) and it is thought that the amino-terminus of insulin binds with L1 on one of the alpha-subunits and the carboxyterminus with L2 on the other alpha-subunit.
The binding of insulin to its receptor causes a conformational change in the alpha-subunits. This in turn produces a conformational change in the beta-subunits leading to the activation of the intrinsic insulin receptor tyrosine kinase.
Almost concomitantly a second effect resulting from the tyrosine phosphorylation of the insulin receptor begins to occur. The phosphorylation of the tyrosine in the NPEY sequence found in the juxtamembrane is also a signal for endocytosis to occur. Whilst invagination of the plasma membrane commences the receptor tyrosine kinase activity continues unabated as does substrate phosphorylation.
As the invagination continues certain proteins are concentrated in the area of invagination. In addition to the insulin receptor itself there is a recruitment of insulin-specific protein tyrosine phosphatases (PTPs). This process takes less than one minute. (The identity of these PTPs is not clearly established yet.)
The formation of the endosome containing the activated ligand-receptor complex is completed within two minutes following ligand presentation at the plasma membrane and is maximal by five minutes. Endocytosis of activated receptors has the dual effect of concentrating receptors within endosomes and allowing the insulin receptor tyrosine kinase to phosphorylate substrates that are spatially distinct from those accessible at the plasma membrane. The endosome also contains other proteins crucial to the signal transduction process. These include a proton pump and the insulin degrading activity. It is not certain how these proteins arrive in the endosome since it could be via the endosome maturation or fusion pathways.
The effect of the proton pump is to allow entry of [H+] ions into the lumen of the endosome. The net effect of this is to lower the pH of the lumen from pH 7.4 (the pH at the plasma membrane) to pH 6.0 (documented with studies using FITC-labeled insulin - a pH dependent fluorescence marker).
As the endosomal lumen acidifies the insulin dissociates from the insulin receptor making it available for degradation by the insulin degrading activity (IDA) present in the endosomal membrane.
At the beginning of this reaction, 1 molecule of 'insulin' is present.
This reaction takes place in the 'endosome' and is mediated by the 'insulysin activity of IDA (insulin degrading activity' of 'IDA (insulin degrading activity)'.
With insulin dissociated from its receptor the signal to sustain the receptor kinase's activity is also removed. Thus endosomally-associated protein tyrosine phosphatases (PTPs) are able to dephosphorylate the receptor which now can not rephosphorylate themselves since insulin is removed and the receptor is in the inactive protein conformation. (The identity of these PTPs is not clearly established yet.)
The dephosphorylation of the receptor is also a signal for the receptor to recycle back to the plasma membrane.
The endosome fuses with the plasma membrane allowing the insulin receptor to re-integrate there. Any degraded insulin remnants which remained in the endosome are also expelled (The majority having been excreted into the cytoplasm and secreted out of the cell via other mechanisms).
The cycle is complete with the dephosphorylated receptor now back in the plasma membrane available to bind the next insulin molecule presented to it. There is some insulin receptor degradation over time when damaged insulin receptors are not recycled but fuse instead with the lysosomes where they are degraded. However the majority of insulin receptors are recycled back to the plasma membrane with greater than 95% efficiency.
Inactive p21ras:GDP is anchored to the plasma membrane by a farnesyl residue. Insulin stimulation results in phosphorylation of IRS1/2 on tyrosine residues. GRB2 binds the phosphotyrosines via its SH2 domain. As IRS is phosphorylated by the insulin receptor near to the plasma membrane, the GRB2:SOS1:IRS interaction brings SOS1 and p21 Ras into close proximity.
IRS1, IRS2 and IRS3 are all known to bind the regulatory subunit of PI3K via its SH2 domain, an interaction that itself activates the kinase activity of the PI3K catalytic subunit (Rivachandran et al. 2001).
SHC1 interacts via its SH2 domain with the carboxyterminal phosphorylated tyrosines of the insulin receptor. As a result, SHC1 is tyrosine phosphorylated by the insulin receptor, later falling away from the receptor (Liang et al.1999, Sasaoka et al.1996).
SHC1 is tyrosine phosphorylated at Tyr-427 by the insulin receptor, later falling away from the receptor. Phosphorylation of SHC1 allows the SH2 domain of GRB2 to bind it (Sasaoka et al. 2000).
Release of tyrosine-phosphorylated SHC from the insulin receptor triggers a cascade of signalling events via SOS, RAF and the MAP kinases (Sasaoka et al. 1996, Kleiman et al.2011).
This is a black box event since this dissociation is inferred from other reaction which show association and dissociation for this protein under EGF stimulation (Kleiman et al. 2011).
Tyrosine-phosphorylated SHC1 recruits the SH2 domain of the adaptor protein GRB2, which is complexed with SOS, an exchange factor for p21ras and RAC, through its SH3 domain. Besides SOS, the GRB2 SH3 domain can associate with other intracellular targets, including GAB1. Erk and Rsk mediated phosphorylation results in dissociation of the SOS-GRB2 complex. This may explain why Erk activation through Shc and SOS-GRB2 is transient. Inactive p21ras-GDP is found anchored to the plasma membrane by a farnesyl residue. As Shc is phosphorylated by the the stimulated receptor near to the plasma membrane, the SOS-GRB2:Shc interaction brings the SOS enzyme into close proximity to p21ras.
At the beginning of this reaction, 1 molecule of 'phospho-IRS' is present. At the end of this reaction, 1 molecule of 'Orthophosphate', and 1 molecule of 'IRS' are present.
This reaction takes place in the 'cytosol' and is mediated by the 'protein tyrosine phosphatase activity' of 'protein tyrosine phosphatase' (Pederson et al.2001).
At the beginning of this reaction, 1 molecule of 'phospho-SHC' is present. At the end of this reaction, 1 molecule of 'Orthophosphate', and 1 molecule of 'SHC transforming protein' are present.
This reaction takes place in the 'cytosol' and is mediated by the 'protein tyrosine phosphatase activity' of 'protein tyrosine phosphatase' (Sasaoka et al. 1996). This is a black box event since the event of dephosphorylation is inferred from other reaction where this process occurs after other stimulation (Gu et al. 1999).
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The importance of the RAS/RAF MAPK cascade is highlighted by the fact that components of this pathway are mutated with high frequency in a large number of human cancers. Activating mutations in RAS are found in approximately one third of human cancers, while ~8% of tumors express an activated form of BRAF (Roberts and Der, 2007; Davies et al, 2002; Cantwell-Dorris et al, 2011).
Annotated Interactions
This reaction takes place on the 'internal side of plasma membrane' and is mediated by the 'kinase activity' of 'ERK1'.
This reaction takes place on the 'internal side of plasma membrane' and is mediated by the 'transmembrane receptor protein tyrosine kinase activity' of 'IRS:activated insulin receptor'.
This reaction takes place on the 'internal side of plasma membrane'. In Fao or NIH3T3 cells stably expressing IR, overexpression of PKCζ enhances the dissociation from IR and decrease in IRS1 tyrosine phosphorylation caused by prolonged insulin stimulation (Riu et al. 2001, Ravichandran et al. 2001).
The binding of insulin to its receptor causes a conformational change in the alpha-subunits. This in turn produces a conformational change in the beta-subunits leading to the activation of the intrinsic insulin receptor tyrosine kinase.
As the invagination continues certain proteins are concentrated in the area of invagination. In addition to the insulin receptor itself there is a recruitment of insulin-specific protein tyrosine phosphatases (PTPs). This process takes less than one minute. (The identity of these PTPs is not clearly established yet.)
The formation of the endosome containing the activated ligand-receptor complex is completed within two minutes following ligand presentation at the plasma membrane and is maximal by five minutes. Endocytosis of activated receptors has the dual effect of concentrating receptors within endosomes and allowing the insulin receptor tyrosine kinase to phosphorylate substrates that are spatially distinct from those accessible at the plasma membrane. The endosome also contains other proteins crucial to the signal transduction process. These include a proton pump and the insulin degrading activity. It is not certain how these proteins arrive in the endosome since it could be via the endosome maturation or fusion pathways.
This reaction takes place in the 'endosome' and is mediated by the 'insulysin activity of IDA (insulin degrading activity' of 'IDA (insulin degrading activity)'.
The dephosphorylation of the receptor is also a signal for the receptor to recycle back to the plasma membrane.
The cycle is complete with the dephosphorylated receptor now back in the plasma membrane available to bind the next insulin molecule presented to it. There is some insulin receptor degradation over time when damaged insulin receptors are not recycled but fuse instead with the lysosomes where they are degraded. However the majority of insulin receptors are recycled back to the plasma membrane with greater than 95% efficiency.
This reaction takes place in the 'cytosol' and is mediated by the 'protein tyrosine phosphatase activity' of 'protein tyrosine phosphatase' (Pederson et al.2001).
This reaction takes place in the 'cytosol' and is mediated by the 'protein tyrosine phosphatase activity' of 'protein tyrosine phosphatase' (Sasaoka et al. 1996).
This is a black box event since the event of dephosphorylation is inferred from other reaction where this process occurs after other stimulation (Gu et al. 1999).