MOUSE P87(WEE1) KINASE IS REGULATED BY M-PHASE SPECIFIC PHOSPHORYLATION

We have cloned a mouse wee1 kinase cDNA (mwee1). The clone is 2258 bp in length and its open reading frame corresponds to 646 amino acid res idues. The molecular weight of this kinase is 87 kDa in SDS PAGE, whic h is about 1.7-fold larger than the human p50(wee1) kinase reported pr eviously. In a cell cycle, the mouse wee1 kinase Is phosphorylated at M-phase, and an in vitro study using a mitotic extract revealed that p hosphorylation occurs in the N-terminal domain, which is absent from t he human wee1 kinase, resulting in inactivation of the kinase activity . The N-terminal domain or entire molecule is extensively phosphorylat ed by cdc2-cyclin a kinase. Furthermore, the activity of the wee1 kina se was reduced by phosphorylation with the mitotic extract which conta ined cdc2-cyclin B kinase