pp60c-src variants containing lesions that affect phosphorylation at tyrosines 416 and 527.

摘要: The biological and biochemical properties of pp60c-src are regulated, in part, by phosphorylation at Tyr-416 Tyr-527. tyrosine kinase transforming activities suppressed Tyr-527, whereas full activation requires Tyr-416. To test specifically the significance negatively charged phosphate moieties on these residues, we have substituted codons for both residues with either Glu or Gln. A position 527 was unable to mimic a phosphorylated Tyr this position, and, consequence, mutated activated transforming. Similarly, substitution stimulate enzyme. However, mutagenesis Gln (to form mutant 416Q) activity approximately twofold over that observed wild-type pp60c-src. When introduced into 527F (containing Phe-527 instead Tyr), double 416Q-527F exhibited weak activity. This is contrast other mutants 416E-527F 416F-527F, which were nontransforming. basis 416Q activates not understood but probably involves some local conformational perturbation. Deletion 519 524 (RH5), region previously shown be necessary association middle-T antigen, led loss Tyr-527 enzymatic focus-forming Hence, sequences complex formation antigen may also required kinase(s) phosphorylates vivo. suggests normal cells contain cellular proteins analogous whose action regulates controlling dephosphorylation residue 527.