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Catalytic domain of the Protein Tyrosine Kinase, Wee1b PTKs catalyze the transfer of the gamma-phosphoryl group from ATP to tyrosine (tyr) residues in protein substrates. This subfamily is composed of human Wee1b (also called Wee2), Xenopus laevis Wee1a (XeWee1a) and similar vertebrate proteins. XeWee1a accumulates after exiting the metaphase II stage in oocytes and in early mitotic cells. It functions during the first zygotic cell division and not during subsequent divisions. Mammalian Wee2/Wee1b is an oocyte-specific inhibitor of meiosis that functions downstream of cAMP. Wee1 is a cell cycle checkpoint kinase that helps keep the cyclin-dependent kinase CDK1 in an inactive state through phosphorylation of an N-terminal tyr (Y15) residue. During the late G2 phase, CDK1 is activated and mitotic entry is promoted by the removal of this inhibitory phosphorylation by the phosphatase Cdc25. Although Wee1 is functionally a tyr kinase, it is more closely related to serine/threonine kinases (STKs). It contains a catalytic kinase domain sandwiched in between N- and C-terminal regulatory domains. It is regulated by phosphorylation and degradation, and its expression levels are also controlled by circadian clock proteins. The Wee1b subfamily is part of a larger superfamily that includes the catalytic domains of STKs, other PTKs, RIO kinases, aminoglycoside phosphotransferase, choline kinase, and phosphoinositide 3-kinase. |
Jiyao W et al.(2023). "The conserved domain database in 2023.",