Requirement for integration of signals from two distinct phosphorylation pathways for activation of MAP kinase

摘要: MAP kinase (relative molecular mass, 42,000), a low abundance serine-threonine protein kinase, is transiently activated in many cell types by variety of mitogens, including insulin, epidermal growth factor, and phorbol esters1,2. In vitro, will phosphorylate reactivate S6 II previously inactivated phosphatase treatment3. Because the stimuli that activate are also stimulators proliferation, regulation cycle seems to involve network kinases, could be important transmission eventually leading progression from GO Gl cycle. Activated contains both phosphotyrosine phosphothreonine4. We report here can deactivated completely treatment with either 2A, specific for phosphoserine phosphothreonine, or CD45, phosphotyrosine-specific phosphatase. demonstrate only active when tyrosyl threonyl residues phosphorylated suggest therefore enzyme functions vivo integrate signals two distinct transduction pathways.