HUMAN WEE1 KINASE INHIBITS CELL-DIVISION BY PHOSPHORYLATING P34(CDC2) EXCLUSIVELY ON TYR15

被引:416
作者
MCGOWAN, CH [1 ]
RUSSELL, P [1 ]
机构
[1] Scripps Res Inst, DEPT CELL BIOL, LA JOLLA, CA 92037 USA
关键词
CELL CYCLE; CYCLIN-B; CDC2; PHOSPHORYLATION; WEE1;
D O I
10.1002/j.1460-2075.1993.tb05633.x
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
In fission yeast, the M-phase inducing kinase, a complex of p34cdc2 and cyclin B, is maintained in an inhibited state during interphase due to the phosphorylation of Cdc2 at Tyr15. This phosphorylation is believed to be carried out primarily by the Weel kinase. In human cells the negative regulation of p34cdc2/cyclin B is more complex, in that Cdc2 is phosphorylated at two inhibitory sites, Thr14 and Tyr15. The identities of the kinases that phosphorylate these sites are unknown. Since fission yeast Wee1 kinase behaves as a dual-specificity kinase in vitro, a popular hypothesis is that a human Weel homolog might phosphorylate p34cdc2 at both sites. We report here that a human gene, identified as a possible Weel homologue, blocks cell division when overexpressed in HeLa cells. This demonstrates functional conservation of the Weel mitotic inhibitor. Contrary to the dual-specificity kinase hypothesis, purified human Wee1 phosphorylates p34cdc2 exclusively on Tyr15 in vitro; no Thr14 phosphorylation was detected. Human and fission yeast Weel also specifically phosphorylate synthetic peptides at sites equivalent to Tyr15. Mutation of a critical lysine codon (Lys114) believed to be essential for kinase activity abolished both the in vivo mitotic inhibitor function and in vitro kinase activities of human Wee1. These results conclusively prove that Wee1 kinases inhibit mitosis by directly phosphorylating p34cdc2 on Tyr15, and strongly indicate that human cells have independent kinase pathways directing the two inhibitor phosphorylations of p34cdc2.
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页码:75 / 85
页数:11
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