Okuzaki D, Tanaka S, Kanazawa H, Nojima H
Department of Molecular Genetics, Research Institute for Microbial Diseases, Osaka University, Suita City, Japan.
Genes Cells. 1997 Dec;2(12):753-70. doi: 10.1046/j.1365-2443.1997.1590358.x.
A number of proteins make up the Cdc28 complex in Saccharomyces cerevisiae, and regulate CDK activity. The cell cycle regulator Nik1 (Hsl1) is a protein kinase that interacts with the Cdc28 complex. The growth inhibitor Gin4 is structurally similar to Nik1 and may play a redundant role in the regulation of the cell cycle. We investigated the functions of Gin4 with respect to those of Nik1.
GIN4 was not essential for growth, and cells deficient in the GIN4 gene displayed no obvious defects in cell cycle regulation. The delta(gin)4 delta(nik)1 strain was temperature sensitive and showed an abnormal cell shape and FACS profile at permissive temperatures. GFP-fused Gin4 was localized at the bud-neck from late G1 to the M phase. Over-production of the C-terminal portion of Gin4 was toxic for cell growth, and this domain was required for the bud-neck localization of Gin4-GFP. High copy expression of Gin4-GFP disturbed the bud-neck localization of Gin4 in the abnormally elongated cells. Cytokinesis was defective in the delta(gin)4 cdc28 double mutants. The GST-Gin4 fusion protein physically associates with the Cdc28 complex.
Gin4 is a bud-neck protein. GIN4 and NIK1 have distinct but partially overlapping functions. The major function of GIN4 is to ensure proper mitotic progression and cytokinesis.
酿酒酵母中的多种蛋白质构成Cdc28复合物，并调节CDK活性。细胞周期调节因子Nik1（Hsl1）是一种与Cdc28复合物相互作用的蛋白激酶。生长抑制剂Gin4在结构上与Nik1相似，可能在细胞周期调控中发挥冗余作用。我们研究了Gin4相对于Nik1的功能。
GIN4对生长不是必需的，缺乏GIN4基因的细胞在细胞周期调控中没有明显缺陷。Δ(gin)4Δ(nik)1菌株对温度敏感，在允许温度下表现出异常的细胞形态和FACS图谱。GFP融合的Gin4在G1晚期到M期定位于芽颈。Gin4 C末端部分的过量表达对细胞生长有毒，该结构域是Gin4-GFP芽颈定位所必需的。Gin4-GFP的高拷贝表达扰乱了异常伸长细胞中Gin4的芽颈定位。Δ(gin)4 cdc28双突变体中的胞质分裂存在缺陷。GST-Gin4融合蛋白与Cdc28复合物发生物理结合。
Gin4是一种芽颈蛋白。GIN4和NIK1具有不同但部分重叠的功能。GIN4的主要功能是确保有丝分裂的正常进行和胞质分裂。
