Molecular characterization of Ypi1, a novel Saccharomyces cerevisiae type 1 protein phosphatase inhibitor
Molecular characterization of Ypi1, a novel Saccharomyces cerevisiae type 1 protein phosphatase inhibitor
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DOI：
10.1074/jbc.m306157200
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发表时间：
2003-11-28
影响因子：
4.8
通讯作者：
Sanz, P
中科院分区：
文献类型：
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作者：
García-Gimeno, MA;Muñoz, I;Sanz, P
酿酒酵母开放阅读框架YFR 003 c编码一个小的（155个氨基酸）亲水性蛋白，我们确定为一种新的，热稳定的抑制剂1型蛋白磷酸酶（Ypi 1）。Ypi 1在体外与Glc 7和Ppz 1磷酸酶催化亚基物理相互作用，如下拉测定所示。Ypi 1抑制Glc 7，但似乎是对Ppz 1磷酸酶活性在测试条件下的有效性较低。Ypi 1含有一个（RHNVRW 53）-R-48序列，它类似于特征性的共有PP 1磷酸酶结合基序。该基序中的W53 A突变消除了Glc 7和Ppz 1磷酸酶的结合和抑制。YPI 1的缺失是致命的，这表明抑制剂在酵母生理学中的相关作用。过表达Ypi 1的细胞表现出许多与该蛋白对Glc 7的抑制作用一致的表型，例如在slt 2/mpk 1促分裂原活化蛋白激酶缺陷背景中糖原含量降低和生长缺陷增加。综合考虑，这些结果将Ypi 1定义为在芽殖酵母中鉴定的Glc 7的第一个抑制性亚基。
The Saccharomyces cerevisiae open reading frame YFR003c encodes a small (155-amino acid) hydrophilic protein that we identified as a novel, heat-stable inhibitor of type 1 protein phosphatase (Ypi1). Ypi1 interacts physically in vitro with both Glc7 and Ppz1 phosphatase catalytic subunits, as shown by pull-down assays. Ypi1 inhibits Glc7 but appears to be less effective toward Ppz1 phosphatase activity under the conditions tested. Ypi1 contains a (RHNVRW53)-R-48 sequence, which resembles the characteristic consensus PP1 phosphatase binding motif. A W53A mutation within this motif abolishes both binding to and inhibition of Glc7 and Ppz1 phosphatases. Deletion of YPI1 is lethal, suggesting a relevant role of the inhibitor in yeast physiology. Cells overexpressing Ypi1 display a number of phenotypes consistent with an inhibitory role of this protein on Glc7, such as decreased glycogen content and an increased growth defect in a slt2/mpk1 mitogen-activated protein kinase-deficient background. Taking together, these results define Ypi1 as the first inhibitory subunit of Glc7 identified in budding yeast.