Human mitotic spindle-associated protein PRC1 inhibits MgcRacGAP activity toward Cdc42 during the metaphase
Human mitotic spindle-associated protein PRC1 inhibits MgcRacGAP activity toward Cdc42 during the metaphase
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DOI：
10.1074/jbc.m313257200
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发表时间：
2004-04-16
影响因子：
4.8
通讯作者：
Tanaka, H
中科院分区：
文献类型：
--
作者：
Ban, R;Irino, Y;Tanaka, H
虽然许多蛋白质已被证明参与有丝分裂事件，包括胞质分裂，他们的具体作用和相互作用仍然不清楚。本报告证明了一种新的蛋白质相互作用。酵母双杂交筛选使用PRC 1（蛋白质调节胞质分裂1）cDNA，一个人的有丝分裂纺锤体相关的细胞周期蛋白依赖性激酶（CDK）的底物，这是参与胞质分裂，作为诱饵进行。数据显示PRC 1诱饵结合MgcRacGAP，MgcRacGAP是Rho家族GTP酶的GTP酶激活蛋白（GAP），也参与胞质分裂。此外，这两种蛋白质在M期表现出相似的定位。PRC 1被证明可以结合到MgcRacGAP的COOH末端GAP保守结构域，并抑制其对Cdc 42的GAP活性。发现MgcRacGAP GAP活性的这种结合和/或抑制依赖于PRC 1与MgcRacGAP的碱性区（125 - 285个氨基酸）的进一步结合。此外，碱性区域被Aurora B激酶磷酸化，这种磷酸化阻止了PRC 1对GAP活性的抑制。过表达MgcRacGAP的磷酸化模拟突变体的细胞在中期表现出纺锤体形态的异常。Cdc 42在有丝分裂中期表现出高活性，定位于纺锤体和中心体。我们认为PRC 1在中期下调MgcRacGAP差距活性，从而有助于纺锤体的正确形成。
Although many proteins have been shown to participate in mitotic events, including cytokinesis, their specific roles and interactions remain unclear. A novel interaction of proteins is demonstrated in this report. Yeast two-hybrid screening using PRC1 (protein-regulating cytokinesis 1) cDNA, a human mitotic spindle-associated cyclin-dependent kinase (CDK) substrate, which is involved in cytokinesis, as bait was performed. Data show that the PRC1 bait bound to MgcRacGAP, which is a GTPase-activating protein ( GAP) for the Rho family GTPases also involved in cytokinesis. In addition, the two proteins showed similar localization during the Mphase. PRC1 was shown to bind to the COOH-terminal GAP-conserved domain of MgcRacGAP and to inhibit its GAP activity toward Cdc42. This binding and/or inhibition of MgcRacGAP GAP activity was found to depend on further binding of PRC1 to the basic region ( 125 - 285 amino acids) of MgcRacGAP. Furthermore, the basic region was phosphorylated with Aurora B kinase, and this phosphorylation prevented the inhibition of GAP activity by PRC1. Cells overexpressing a phosphorylation mimic mutant of MgcRacGAP exhibited an abnormality of spindle morphology in the metaphase. Cdc42 showed high activity and was localized to the mitotic spindles and centrosomes during the metaphase. We propose that PRC1 down-regulates the GAP activity of MgcRacGAP during the metaphase and thereby contributes to the correct formation of the spindle.