激素作用的机制 Peptide hormones(H)cannot enter their target cells and must combine with membrane receptors(R)that initiate signal transduction processes. (1)蛋白质或多肽激素 second messenger R mechanisms Opens ion channel Second messenger system phosphorylate KEY Proteins TK =Tyrosine kinase AE=Amplifier enzyme Cellular G=G protein response 激素作用的机制 (1)蛋白质或多肽激素 second messenger mechanisms