Konishi H, Kuroda S, Tanaka M, Matsuzaki H, Ono Y, Kameyama K, Haga T, Kikkawa U
Biosignal Research Center, Kobe University, Japan.
Biochem Biophys Res Commun. 1995 Nov 13;216(2):526-34. doi: 10.1006/bbrc.1995.2654.
cDNA clones encoding the third member of the RAC protein kinase family, termed RAC-PK gamma, were isolated from a rat brain cDNA library. The deduced amino acid sequence of RAC-PK gamma was highly related to those of previously identified family members, RAC-PK alpha and beta, that have a pleckstrin homology domain and a protein-serine/threonine kinase catalytic domain at the amino- and carboxyl-terminal regions, respectively. Northern blot analysis indicated that RAC-PK gamma was expressed abundantly in brain and testis. Specific activities of RAC-PK alpha, beta, and gamma purified from transfected COS-7 cells were similar when measured by using myelin basic protein as a phosphate acceptor. Analysis using fusion proteins of glutathione S-transferase revealed that the pleckstrin homology domain of the three subtypes of RAC-PK associate with both protein kinase C subspecies and beta gamma subunits of G proteins. These results suggest that the pleckstrin homology domains of RAC protein kinase family could associate more than one protein to regulate the activity and/or intracellular distribution of this enzyme family by different ways.
从大鼠脑cDNA文库中分离出编码RAC蛋白激酶家族第三个成员（称为RAC-PKγ）的cDNA克隆。RAC-PKγ推导的氨基酸序列与先前鉴定的家族成员RAC-PKα和β的序列高度相关，RAC-PKα和β分别在氨基末端和羧基末端区域具有普列克底物蛋白同源结构域和蛋白丝氨酸/苏氨酸激酶催化结构域。Northern印迹分析表明，RAC-PKγ在脑和睾丸中大量表达。当使用髓鞘碱性蛋白作为磷酸受体进行测量时，从转染的COS-7细胞中纯化的RAC-PKα、β和γ的比活性相似。使用谷胱甘肽S-转移酶融合蛋白进行的分析表明，RAC-PK三种亚型的普列克底物蛋白同源结构域与蛋白激酶C亚类和G蛋白的βγ亚基都相关。这些结果表明，RAC蛋白激酶家族的普列克底物蛋白同源结构域可以与不止一种蛋白质结合，以不同方式调节该酶家族的活性和/或细胞内分布。
