Small GTP-binding proteins in bovine aortic smooth muscle.
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.
Kawahara
Y
Y
Department of Internal Medicine, 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
D000818:Animals; D001011:Aorta / Q000737:chemistry / Q000378:metabolism*; D002417:Cattle; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D003600:Cytosol / Q000737:chemistry / Q000378:metabolism; D015180:Electrophoresis, Gel, Two-Dimensional; D004591:Electrophoresis, Polyacrylamide Gel; D019204:GTP-Binding Proteins / Q000302:isolation & purification / Q000378:metabolism* / Q000502:physiology; D008970:Molecular Weight; D009131:Muscle, Smooth, Vascular / Q000737:chemistry / Q000378:metabolism*
D019204:GTP-Binding Proteins