Tyrosine phosphorylation of the EGF receptor by the kinase Jak2 is induced by growth hormone

摘要: When growth hormone binds to its receptor, which belongs the cytokine receptor superfamily1, it activates Janus kinase Jak22 has tyrosine-kinase activity and initiates an activation of several key intracellular proteins (for example, mitogen-activated protein (MAP) kinases3,4,5,6) that eventually execute biological actions induced by hormone, including expression particular genes. In contrast receptors themselves have tyrosine activity, signalling pathways leading MAP activation7,8 are triggered poorly understood, but appear be mediated Grb2 Shc9. We now show stimulates phosphorylation for epidermal factor (EGFR) association with at same time in liver, important target tissue hormone. Expression EGFR mutants revealed growth-hormone-induced transcription c-fos requires tyrosines on EGFR, not own intrinsic activity. Moreover, residue 1,068 is proposed one principal sites Grb2-binding stimulated via Jak2. Our results indicate role phosphorylated Jak2, thereby providing docking activating kinases gene expression, independently EGFR. This may represent a novel cross-talk pathway between superfamily receptor.