SRC HOMOLOGY-2 DOMAINS OF PROTEIN-TYROSINE-PHOSPHATASE ARE ASSOCIATED IN-VITRO WITH BOTH THE INSULIN-RECEPTOR AND INSULIN-RECEPTOR SUBSTRATE-1 VIA DIFFERENT PHOSPHOTYROSINE MOTIFS

To clarify the role of protein tyrosine phosphatase containing Src homology 2 (SH2) regions on insulin signaling, we investigated the interactions among the insulin receptor, a pair of SH2 domains of SH-PTP2 coupled to glutathione-S-transferase (GST) and insulin receptor substrate-1 (IRS-1)-GST fusion proteins (amino-portion, IRS-1N; carboxyl portion, IRS-1C). GST-SH2 protein of SH-PTP2 bound to the wild type insulin receptor, but not to that with a carboxyl-terminal mutation (Y/F2). Furthermore, even though Y/F2 receptors were used, the SH2 protein was also co-immunoprecipitated with IRS-1C, but not with IRS-1N. These results indicate that SH2 domains of SH-PTP2 can directly associate with the Y(1322)TXM motif on the carboxyl terminus of insulin receptors and also may bind to the carboxyl portion of IRS-1, possibly via the Y(1172)IDL motif in vitro.