Shk1, a homolog of the Saccharomyces cerevisiae Ste20 and mammalian p65PAK protein kinases, is a component of a Ras/Cdc42 signaling module in the fission yeast Schizosaccharomyces pombe.

We describe a protein kinase, Shk1, from the fission yeast Schizosaccharomyces pombe, which is structurally related to the Saccharomyces cerevisiae Ste20 and mammalian p65PAK protein kinases. We provide genetic evidence for physical and functional interaction between Shk1 and the Cdc42 GTP-binding protein required for normal cell morphology and mating in S. pombe. We further show that expression of the STE20 gene complements the shk1 null mutation and that Shk1 is capable of signaling to the pheromone-responsive mitogen-activated protein kinase cascade in S. cerevisiae. Our results lead us to propose that signaling modules composed of small GTP-binding proteins and protein kinases related to Shk1, Ste20, and p65PAK, are highly conserved in evolution and participate in both cytoskeletal functions and mitogen-activated protein kinase signaling pathways. IMAGES:

本研究报道了来自粟酒裂殖酵母（Schizosaccharomyces pombe）的蛋白激酶Shk1，其结构与酿酒酵母（Saccharomyces cerevisiae）Ste20以及哺乳动物p65PAK蛋白激酶具有同源性。我们通过遗传学实验证实，Shk1与Cdc42 GTP结合蛋白（Cdc42 GTP-binding protein）之间存在物理与功能相互作用，而该结合蛋白是粟酒裂殖酵母维持正常细胞形态与完成交配过程所必需的。我们进一步发现，STE20基因的表达可互补shk1基因无效突变的表型，且Shk1能够在酿酒酵母中介导信息素响应型丝裂原活化蛋白激酶（mitogen-activated protein kinase）级联信号通路的信号转导。基于上述研究结果，我们提出：由小型GTP结合蛋白以及与Shk1、Ste20、p65PAK同源的蛋白激酶构成的信号模块在进化过程中高度保守，且同时参与细胞骨架功能与丝裂原活化蛋白激酶信号通路。IMAGES: