Protein phosphorylation, which is mediated by enzymes, called protein kinases, is a major mechanism for transducing external stimuli into intracellular signals.

• 在这其中，把细胞外刺激转导到细胞内是通过蛋白质磷酸化来完成的，而蛋白质磷酸化又被蛋白激酶介导。