Xenopus MAP kinase activator: identification and function as a key intermediate in the phosphorylation cascade.

摘要: MAP kinase is thought to play a pivotal role not only in the growth factor-stimulated signalling pathway but also M phase phosphorylation cascade downstream of MPF. fully active when both tyrosine and threonine/serine residues are phosphorylated. We have now identified purified Xenopus activator from mature oocytes that able induce activation on an inactive form kinase. The itself 45 kDa phosphoprotein inactivated by protein phosphatase 2A treatment vitro. Microinjection into immature results immediate Further experiments using microinjection as well cell free extracts shown intermediate between MPF Thus, plays key cascade.