Kawahara Y, Kawata M, Sunako M, Araki S, Koide M, Tsuda T, Fukuzaki H, Takai Y
Department of Internal Medicine (1st Division), Kobe University, School of Medicine, Japan.
Biochem Biophys Res Commun. 1990 Jul 31;170(2):673-83. doi: 10.1016/0006-291x(90)92144-o.
In bovine aortic smooth muscle, about 50% of total GTP-binding activity was present in the cytosol fraction. A major GTP-binding protein (G protein) with a Mr value of about 21,000 (21K G) in this fraction was purified to near homogeneity and characterized. 21K G bound maximally about 0.8 mol of [35S]guanosine 5'-(3-O-thio)triphosphate/mol of protein with a Kd value of about 20 nM. 21K G showed GTPase activity with a turnover number of about 0.007 min-1. 21K G was ADP-ribosylated by botulinum ADP-ribosyltransferase and about 0.4 mol of ADP-ribose was maximally incorporated into 1 mol of 21K G. 21K G and the bovine brain rhoA gene product (rhoA p21) were eluted at the same retention time on C4 reversed-phase high performance liquid chromatography and migrated at the same positions on two-dimensional gel electrophoresis. These results indicate that the major G protein in bovine aortic smooth muscle cytosol is rhoA p21.
在牛主动脉平滑肌中，约50%的总GTP结合活性存在于胞质溶胶部分。该部分中一种主要的GTP结合蛋白（G蛋白），其Mr值约为21,000（21K G），被纯化至接近均一状态并进行了特性分析。21K G与[35S]鸟苷5'-（3-O-硫代）三磷酸的最大结合量约为0.8摩尔/摩尔蛋白，Kd值约为20 nM。21K G表现出GTP酶活性，转换数约为0.007 min-1。21K G被肉毒杆菌ADP-核糖基转移酶进行ADP-核糖基化，最大约0.4摩尔的ADP-核糖被掺入1摩尔的21K G中。在C4反相高效液相色谱上，21K G和牛脑rhoA基因产物（rhoA p21）在相同的保留时间被洗脱，在二维凝胶电泳上迁移至相同位置。这些结果表明，牛主动脉平滑肌胞质溶胶中的主要G蛋白是rhoA p21。
