Kawahara Y, Kawata M, Sunako M, Araki S, Koide M, Tsuda T, Fukuzaki H, Takai Y
Department of Internal Medicine, Kobe University School of Medicine, Japan.
Jpn Circ J. 1991 Oct;55(10):1036-43. doi: 10.1253/jcj.55.1036.
In bovine aortic smooth muscle, GTP-binding activity was equally distributed in the membrane and cytosol fractions. The most abundant GTP-binding proteins (G proteins) in each fraction were purified to near homogeneity and characterized. The most abundant G protein in the membrane fraction had a Mr value of about 22,000 (m22K G) as estimated on sodium dodecyl sulfate-polyacryl-amide gel electrophoresis (SDS-PAGE). m22K G and the human platelet smg p21, a ras p21 like G protein having the same effector domain as ras p21s, were eluted at the same retention time on C4 reversed-phase high performance liquid chromatography (HPLC). Moreover, m22K G was specifically recognized by an anti-smg p21 polyclonal antibody. m22K G was phosphorylated by cyclic AMP-dependent protein kinase with a stoichiometry of one phosphate/molecule of protein. The most abundant G protein in the cytosol fraction had a Mr value of about 21,000 (c21K G) as estimated on SDS-PAGE. c21K G was ADP-ribosylated by botulinum ADP-ribosyltransferase and about 0.4 mol of ADP-ribose was maximally incorporated into 1 mol of c21K G. c21K G and the bovine brain rhoA p21, another ras p21 like G protein, were eluted at the same retention time on C4 reversed-phase HPLC and migrated at the same position on two-dimensional gel electrophoresis. These results indicate that the major G proteins in the membrane and cytosol fractions of bovine aortic smooth muscle are smg p21 and rhoA p21, respectively. Possible roles of these G proteins in vascular smooth muscle are discussed.
在牛主动脉平滑肌中，GTP结合活性在膜和胞质溶胶部分中均匀分布。每个部分中最丰富的GTP结合蛋白（G蛋白）被纯化至接近均一，并进行了表征。膜部分中最丰富的G蛋白在十二烷基硫酸钠-聚丙烯酰胺凝胶电泳（SDS-PAGE）上估计的Mr值约为22,000（m22K G）。m22K G与人血小板smg p21（一种与ras p21具有相同效应结构域的ras p21样G蛋白）在C4反相高效液相色谱（HPLC）上以相同的保留时间洗脱。此外，m22K G被抗smg p21多克隆抗体特异性识别。m22K G被环磷酸腺苷依赖性蛋白激酶磷酸化，化学计量比为每分子蛋白一个磷酸基团。胞质溶胶部分中最丰富的G蛋白在SDS-PAGE上估计的Mr值约为21,000（c21K G）。c21K G被肉毒杆菌ADP-核糖基转移酶ADP-核糖基化，每1摩尔c21K G最大可掺入约0.4摩尔ADP-核糖。c21K G与牛脑rhoA p21（另一种ras p21样G蛋白）在C4反相HPLC上以相同的保留时间洗脱，并在二维凝胶电泳上迁移到相同位置。这些结果表明，牛主动脉平滑肌膜和胞质溶胶部分中的主要G蛋白分别是smg p21和rhoA p21。讨论了这些G蛋白在血管平滑肌中的可能作用。
