Insulin receptor substrate-2 binds to the insulin receptor through its phosphotyrosine-binding domain and through a newly identified domain comprising amino acids 591-786.
We compared the interaction between the insulin receptor (IR) and the IR substrate (IRS) proteins IRS-1 and IRS-2) using the yeast two-hybrid system. Both IRS proteins interact specifically with the cytoplasmic portion of the IR and the related insulin-like growth factor-I receptor, and these interactions require receptor tyrosine kinase activity. Alignment of IRS-1 and IRS-2 revealed two conserved domains at the NH2 terminus, called IH1PH and IH2PTB, which resemble a pleckstrin homology (PH) domain and a phosphotyrosine binding (PTB) domain, respectively. The IH2PTB binds to the phosphorylated NPXY motif (Tyr-960) in the activated insulin receptor, providing a specific mechanism for the interaction between the receptor and IRS-1. Although the IH2PTB of IRS-2 also interacts with the NPEY motif of the insulin receptor, it is not essential for the interaction between the insulin receptor and IRS-2 in the yeast two-hybrid system. IRS-2 contains another interaction domain between residues 591 and 786, which is absent in IRS-1. This IRS-2-specific domain is independent of the IH2PTB and does not require the NPEY motif; however, it requires a functional insulin receptor kinase and the presence of three tyrosine phosphorylation sites in the regulatory loop (Tyr-1146, Tyr-1150, and Tyr-1151). Importantly, this novel domain mediates the association between IRS-2 and insulin receptor lacking the NPXY motif and may provide a mechanism by which the stoichiometry of regulatory loop autophosphorylation enhances IRS-2 phosphorylation.
Sawka-Verhelle
D
D
INSERM U145, Nice, France.
Tartare-Deckert
S
S
White
M F
MF
Van Obberghen
E
E
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D017931:DNA Primers; D066298:In Vitro Techniques; D055504:Insulin Receptor Substrate Proteins; D051379:Mice; D008969:Molecular Sequence Data; D010750:Phosphoproteins / Q000235:genetics* / Q000378:metabolism*; D010766:Phosphorylation; D019000:Phosphotyrosine / Q000378:metabolism; D017526:Receptor, IGF Type 1 / Q000235:genetics / Q000378:metabolism; D011972:Receptor, Insulin / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism
D017931:DNA Primers; D055504:Insulin Receptor Substrate Proteins; C526295:Irs1 protein, mouse; D010750:Phosphoproteins; D011994:Recombinant Proteins; D019000:Phosphotyrosine; D017526:Receptor, IGF Type 1; D011972:Receptor, Insulin