Distinguishing between A Mitogenic and Two Closely Related Nonmitogenic Protein Kinases

摘要

Protein kinases are key components in the signal transduction pathways that transmit extemal membrane-directed signals to the cell nucleas. These enzymes share a strong primary sequence homology as well as a common substrate (i.e., ATP), yet they participate io a vast array of often unrelated signaling cascades. For example, one role of the cAMP-dependent protein kinase ("PKA"')2 is to regulate the enzyrnes of glycogen metabolism, whereas a function of the cGMP-dependent protein kinase ("PKG") is toparticipate ia nitric oxide-induced signaling. In addition, protein kinase C ("PKC") serves as the receptor for the phorbol ester tumor promoters and has been strongly implicated in mitogenesis.