title: Dephosphorylation of insulin receptor substrate 1 by the tyrosine phosphatase PTP2C.
abstract: The phosphotyrosine (Tyr(P)) form of insulin receptor substrate 1 (IRS-1) is a key component in insulin signaling. Our previous study revealed that Tyr(P) IRS-1 binds to the widely distributed tyrosine phosphatase PTP2C through the src homology 2 (SH2) domains of the latter. In the present study, we examined the activity of this enzyme and of a truncated form lacking the SH2 domains (delta PTP2C) toward IRS-1 and also toward the cytoplasmic domain of the insulin receptor. Tyr(P) IRS-1 was prepared by phosphorylation of recombinant IRS-1 with recombinant cytoplasmic insulin receptor kinase (CIRK). PTP2C rapidly dephosphorylated Tyr(P) IRS-1; dephosphorylation by delta PTP2C was approximately one-third as fast. Other substrates, including Tyr(P) CIRK, were not dephosphorylated as rapidly by PTP2C; moreover, delta PTP2C was at least 10 times more active than PTP2C toward CIRK and other substrates. These results indicate that the binding of Tyr(P) residues on IRS-1 to the SH2 domain(s) of PTP2C enhances its activity toward IRS-1 and suggest that PTP2C is the phosphatase responsible for the dephosphorylation of IRS-1 in vivo. In addition, with the expectation that a PTP2C-resistant form of IRS-1 will be useful in investigations of IRS-1 function, we determined that IRS-1 can be thiophosphorylated with adenosine 5'-O-(3-thiotriphosphate) and CIRK and that this form of IRS-1 is resistant to PTP2C.
authors.affiliation: Department of Biochemistry, Dartmouth Medical School, Hanover, New Hampshire 03755.
authors.forename: M R
authors.initials: MR
authors.lastname: Kuhné
authors.forename: Z
authors.initials: Z
authors.lastname: Zhao
authors.forename: J
authors.initials: J
authors.lastname: Rowles
authors.forename: B E
authors.initials: BE
authors.lastname: Lavan
authors.forename: S H
authors.initials: SH
authors.lastname: Shen
authors.forename: E H
authors.initials: EH
authors.lastname: Fischer
authors.forename: G E
authors.initials: GE
authors.lastname: Lienhard
mesh_terms: D000818:Animals; D006801:Humans; D055504:Insulin Receptor Substrate Proteins; D047908:Intracellular Signaling Peptides and Proteins; D007700:Kinetics; D009036:Moths; D010750:Phosphoproteins / Q000096:biosynthesis / Q000302:isolation & purification / Q000378:metabolism*; D010766:Phosphorylation; D019000:Phosphotyrosine; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases / Q000378:metabolism*; D051381:Rats; D011972:Receptor, Insulin / Q000096:biosynthesis / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D054593:SH2 Domain-Containing Protein Tyrosine Phosphatases; D013379:Substrate Specificity; D014162:Transfection; D014443:Tyrosine / Q000031:analogs & derivatives / Q000032:analysis / Q000378:metabolism
chemical_list: C526292:IRS1 protein, human; D055504:Insulin Receptor Substrate Proteins; D047908:Intracellular Signaling Peptides and Proteins; C526296:Irs1 protein, rat; D010750:Phosphoproteins; D011994:Recombinant Proteins; D019000:Phosphotyrosine; D014443:Tyrosine; D011972:Receptor, Insulin; C516724:PTPN11 protein, human; C509249:PTPN6 protein, human; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases; C516727:Ptpn11 protein, rat; C509250:Ptpn6 protein, rat; D054593:SH2 Domain-Containing Protein Tyrosine Phosphatases