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Control of yeast cell growth by protein phosphorylation dephosphorylation

通过蛋白质磷酸化去磷酸化控制酵母细胞生长

基本信息

批准号：
61480058
负责人：
TOH-E Akio
金额：
$ 4.16万
依托单位：
HIROSHIMA UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1986
资助国家：
日本
起止时间：
1986 至 1987
项目状态：
已结题

项目摘要

Protein kinase is a group of enzymes which regulate various cellular functions by phosphorylating an essential protein(s). Increasing number of protein kinases have been reported these years. Among them, cyclic AMP-dependent protein kinase has been most extensively characterized. The holoenzyme of cAMP-dependent protein kinase is inactive and composed of two catalytic subunits and two regulatory subunits. cAMP binds with the regulatory subunits and then releases active catalytic subunits which, in turn, phosphorylate substrate proteins. Results obtained during the course of this project are summarized as follows.(1) We have cloned and sequenced the BCY1 gene encoding the regulatory subunit of cAMP-dependent protein kinase. The deduced amino acid sequence indicates that the protein contains the consensus sequence for a phosphoruylation site, RRTS. Amino acid substitutions were induced at the presumed phosphorylation site by oligonucleotide directed mutagenesis. One of the the mutant containing RRNA instead of RRTS showed a cold sensitive phenotype, which can be explained by the idea that the RRNA protein acts as an inhibitor of the catalytic subunit at low temperature.(2) We have cloned yeast genes which can complement the ppdl defect which presumably fesulted in the defect of protein phoshphatase.(3) We found that the expression of the polyubiquitin gene (UBI4) is controlled by the cAMP cascade as well as by the heat shock. UBI4 is the first cell cycle related gene which has been shown to be a target of cAMP dependent protein kinase.

蛋白激酶是一组通过磷酸化必需蛋白质来调节各种细胞功能的酶。近年来，越来越多的蛋白激酶被报道。其中，环腺苷酸依赖性蛋白激酶已被最广泛的特点。cAMP依赖性蛋白激酶的全酶是无活性的，由两个催化亚基和两个调节亚基组成。cAMP与调节亚基结合，然后释放活性催化亚基，其反过来磷酸化底物蛋白。现将该项目实施过程中取得的成果总结如下。(1)我们已经克隆并测序了编码cAMP依赖性蛋白激酶调节亚基的BCY 1基因。推导的氨基酸序列表明，该蛋白质含有磷酸化位点，RRTS的共识序列。通过寡核苷酸定向诱变在假定的磷酸化位点诱导氨基酸取代。其中一个含有RRNA而不是RRTS的突变体表现出冷敏感表型，这可以通过RRNA蛋白在低温下作为催化亚基的抑制剂来解释。(2)我们已经克隆了酵母基因，这些基因可以弥补可能由蛋白磷酸酶缺陷引起的ppdl缺陷。(3)我们发现，多聚泛素基因（UBI 4）的表达是由cAMP级联以及热休克控制。UBI 4是第一个被证明是cAMP依赖性蛋白激酶靶点的细胞周期相关基因。