DIFFERENTIAL PHOSPHORYLATION OF VERTEBRATE P34CDC2 KINASE AT THE G1/S AND G2/M TRANSITIONS OF THE CELL-CYCLE - IDENTIFICATION OF MAJOR PHOSPHORYLATION SITES
DIFFERENTIAL PHOSPHORYLATION OF VERTEBRATE P34CDC2 KINASE AT THE G1/S AND G2/M TRANSITIONS OF THE CELL-CYCLE - IDENTIFICATION OF MAJOR PHOSPHORYLATION SITES
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DOI：
10.1002/j.1460-2075.1991.tb07951.x
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发表时间：
1991-02-01
期刊：
影响因子：
11.4
通讯作者：
NIGG, EA
中科院分区：
文献类型：
--
作者：
KREK, W;NIGG, EA
cdc2激酶是真核细胞周期的关键调节因子。其催化亚基p34cdc2的活性受细胞周期依赖的与其他蛋白质的相互作用以及磷酸化-去磷酸化反应的控制。在本文中，我们研究了鸡p34cdc2在细胞周期不同阶段的磷酸化状态。通过多肽定位，我们在鸡p34cdc2中检测到四种主要的磷酸肽；三个磷酸化位点分别为苏氨酸（Thr） 14、酪氨酸（Tyr） 15和丝氨酸（Ser） 277。同步细胞的分析表明，所有四个位点的磷酸化都受细胞周期调节。Thr 14和Tyr 15在G2期磷酸化最多，但在G2/M过渡时突然去磷酸化，伴随p34cdc2激酶的激活。这一结果表明，Thr 14和/或Tyr 15的磷酸化抑制了p34cdc2激酶的活性，这与这些残基在该激酶假定的ATP结合位点内的位置一致。在M期，p34cdc2也被磷酸化，但磷酸化发生在与苏氨酸14不同的苏氨酸残基上。最后，Ser 277的磷酸化在G1期达到峰值，并随着细胞进入S期而显著下降，这提高了这种修饰可能有助于控制脊椎动物p34cdc2激酶的G1/S功能的可能性。
The cdc2 kinase is a key regulator of the eukaryotic cell cycle. The activity of its catalytic subunit, p34cdc2, is controlled by cell cycle dependent interactions with other proteins as well as by phosphorylation-dephosphorylation reactions. In this paper, we examine the phosphorylation state of chicken p34cdc2 at various stages of the cell cycle. By peptide mapping, we detect four major phosphopeptides in chicken p34cdc2; three phosphorylation sites are identified as threonine (Thr) 14, tyrosine (Tyr) 15 and serine (Ser) 277. Analysis of synchronized cells demonstrates that phosphorylation of all four sites is cell cycle regulated. Thr 14 and Tyr 15 are phosphorylated maximally during G2 phase but dephosphorylated abruptly at the G2/M transition, concomitant with activation of p34cdc2 kinase. This result suggests that phosphorylation of Thr 14 and/or Tyr 15 inhibits p34cdc2 kinase activity, in line with the location of these residues within the putative ATP binding site of the kinase. During M phase, p34cdc2 is also phosphorylated, but phosphorylation occurs on a threonine residue distinct from Thr 14. Finally, phosphorylation of Ser 277 peaks during G1 phase and drops markedly as cells progress through S phase, raising the possibility that this modification may contribute to control the proposed G1/S function of the vertebrate p34cdc2 kinase.