Identification of a major GTP-binding protein in bovine aortic smooth muscle cytosol as the rhoA gene product.
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.
Kawahara
Y
Y
Department of Internal Medicine (1st Division), Kobe University, School of Medicine, Japan.
Kawata
M
M
Sunako
M
M
Araki
S
S
Koide
M
M
Tsuda
T
T
Fukuzaki
H
H
Takai
Y
Y
D000246:Adenosine Diphosphate Ribose / Q000378:metabolism; D000818:Animals; D001011:Aorta / Q000032:analysis; D002417:Cattle; D002845:Chromatography; D002851:Chromatography, High Pressure Liquid; D003600:Cytosol / Q000032:analysis; D015180:Electrophoresis, Gel, Two-Dimensional; D019204:GTP-Binding Proteins / Q000032:analysis*; D008565:Membrane Proteins / Q000032:analysis*; D009131:Muscle, Smooth, Vascular / Q000032:analysis*; D020742:rhoA GTP-Binding Protein
D008565:Membrane Proteins; D000246:Adenosine Diphosphate Ribose; D019204:GTP-Binding Proteins; D020742:rhoA GTP-Binding Protein