Sayers L G, Katayama S, Nakano K, Mellor H, Mabuchi I, Toda T, Parker P J
Protein Phosphorylation Laboratory, Imperial Cancer Research Fund, London, UK.
Genes Cells. 2000 Jan;5(1):17-27. doi: 10.1046/j.1365-2443.2000.00301.x.
In metazoans, the HR1 domain, a motif found in a number of proteins including the protein kinase C-related PRKs, is responsible for an interaction with Rho-GTPases. The structural similarity between the Schizosaccaromyces pombe Pck proteins and the mammalian Rho-dependent protein kinase C-related family, has led us to investigate the relationship between the function of Rho and that of Pck1/2.
Rho1 is shown to interact with the conserved N-terminal HR1 domain of Pck1/2 in vitro and in vivo. Lethal overproduction of Rho1 is neutralized by co-expression of the Pck2 HR1 domain, which by itself compromises growth when overproduced. The Pck2-Rho1 interaction has a profound effect on the steady state expression of Pck2 and this is shown to parallel the immunoprecipitated activity and phosphorylation of Pck2 at its activation loop site. It is further shown that Pck2 becomes localized at the septum, where Rho1 is also located.
The results demonstrate that the Pck proteins are Rho1 effectors in fission yeast and that the HR1 domain is a universal motif for the Rho-GTPase interaction. Furthermore, the evidence supports the contention that the yeast Pck1 and Pck2 proteins are primitive protein kinases, which in vertebrates have evolved into the two distinct PKC and PRK families.
在后生动物中，HR1结构域是在包括蛋白激酶C相关的PRKs在内的多种蛋白质中发现的一种基序，负责与Rho - GTP酶相互作用。粟酒裂殖酵母Pck蛋白与哺乳动物Rho依赖性蛋白激酶C相关家族之间的结构相似性，促使我们研究Rho的功能与Pck1/2的功能之间的关系。
Rho1在体外和体内均显示与Pck1/2保守的N端HR1结构域相互作用。Pck2的HR1结构域共表达可中和Rho1的致死性过量表达，而Pck2的HR1结构域自身过量表达时会损害细胞生长。Pck2 - Rho1相互作用对Pck2的稳态表达有深远影响，这与Pck2在其激活环位点的免疫沉淀活性和磷酸化情况平行。进一步表明，Pck2定位于隔膜处，Rho1也位于此处。
结果表明，Pck蛋白是裂殖酵母中的Rho1效应器，并且HR1结构域是Rho - GTP酶相互作用的通用基序。此外，证据支持这样的观点，即酵母Pck1和Pck2蛋白是原始蛋白激酶，在脊椎动物中已进化为两个不同的PKC和PRK家族。
