Enzymatic activation of Fujinami sarcoma virus gag-fps transforming proteins by autophosphorylation at tyrosine.

摘要: Site-directed mutagenesis of the Fujinami sarcoma virus (FSV) genome has suggested that Tyr 1073 P130gag--fps protein-tyrosine kinase is a regulatory site. To investigate directly ability tyrosine phosphorylation to affect activity, phosphotyrosyl phosphatase inhibitor orthovanadate and partially purified phosphatases were used manipulate stoichiometry phosphorylation. Phosphorylation at correlated with enhanced activity. The thermolabile phosphorylation, activity transforming P140gag--fps encoded by temperature-sensitive (ts)FSV variant restored non-permissive temperature for transformation incubation infected cells orthovanadate. In this case can apparently functionally reactivate conditionally defective v-fps These data suggest reversible autophosphorylation conserved within domain positive regulator enzymatic biological function. Phenotypic suppression tsFSV genetic defect emphasizes potential importance in antagonizing action. It may constitute molecular switch which some kinases are activated.