Wang Zhixiang, Moran Michael F
Department of Cell Biology and Signal Transduction Research Group, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, T6G 2H7, Canada.
Mol Interv. 2002 Oct;2(6):352-5,338. doi: 10.1124/mi.2.6.352.
Although phospholipase C-gamma (PLC-gamma) participates in cellular mitogenesis, evidence indicates that the catalytic activity of PLC-gamma (to hydrolyze certain phosphoinositides) is nonessential to the process. So how is it that PLC-gamma is necessary but its lipase activity is not? Recently published results from Snyder and colleagues describe the ability of PLC-gamma to facilitate guanine nucleotide exchange for the recently identified nucleus-localized GTPase PIKE, which acts to enhance the enzymatic activity of phosphatidylinositol 3'-kinase (PI3K). The authors contend that the SH3 domain, rather than the catalytic domain, of PLC-gamma is required for aiding PIKE, and furthermore, that the mitogenic activity of PLC-gamma depends not on its phospholipase activity, but rather on its interaction with PIKE. Wang and Moran examine the results and piece together a picture of how PLC-gamma cooperates with PIKE.
尽管磷脂酶C-γ（PLC-γ）参与细胞有丝分裂，但有证据表明PLC-γ的催化活性（水解某些磷酸肌醇）对该过程并非必不可少。那么，为什么PLC-γ是必需的，但其脂肪酶活性却不是必需的呢？斯奈德及其同事最近发表的研究结果描述了PLC-γ促进鸟嘌呤核苷酸与最近发现的定位于细胞核的GTP酶PIKE进行交换的能力，PIKE的作用是增强磷脂酰肌醇3'-激酶（PI3K）的酶活性。作者认为，PLC-γ的SH3结构域而非催化结构域是辅助PIKE所必需的，此外，PLC-γ的促有丝分裂活性不取决于其磷脂酶活性，而是取决于它与PIKE的相互作用。王和莫兰对这些结果进行了研究，并拼凑出一幅PLC-γ与PIKE如何协同作用的图景。
