Differential activities of protein tyrosine phosphatases in intact cells.

摘要: We have employed transient co-overexpression of protein tyrosine phosphatases (PTPs) with a panel receptor kinases (RTKs) to investigate molecular parameters that regulate dephosphorylation activity and specificity in intact cells. Our results demonstrate clear differences susceptibility various forms different RTKs the action PTP 1B, T-cell phosphatase (TC-PTP), CD45, which suggests cellular compartmentalization as major factor defining overall function. TC-M PTP, nonlocalized cytosolic mutant, is deregulated therefore able efficiently suppress v-erbB- v-fms-induced cell transformation, not observed TC-PTP or 1B. The transmembrane CD45 displays more selectivity but appears be already active during transport surface. Dephosphorylation also dependent on relative RTK/PTP expression levels can modulated by SH2 domain-containing noncatalytic subunit phosphatidylinositol 3'-kinase, p85. Overexpression high affinity binding proteins could contribute RTK-induced transformation cancer.