G protein coupling of human platelet V1 vascular vasopressin receptors.
We used several approaches to identify the G protein coupled to V1 vascular arginine vasopressin (AVP) receptors of human platelets. In purified platelet membranes, high-affinity specific binding of [3H]AVP but not that of the V1 vascular antagonist [3H]d(CH2)5Tyr(Me)AVP was modulated by guanosine 5'-O-(3-thiotriphosphate) or sodium fluoride both in the presence and absence of MgCl2. AVP failed to modify the [alpha-32P]GTP labeling pattern or the cytosolic translocation of the 24- to 27-kDa GTP-binding proteins. AVP-stimulated GTPase activity of platelet membranes was blocked by antibodies specific for the COOH-terminal of the Gq alpha protein. AVP increased labeling of a 42-kDa platelet membrane protein by the photoreactive GTP analogue [alpha-32P]azidoanilido GTP. Immunoblotting of platelet proteins with various G protein-specific antibodies revealed that the 42-kDa protein labeled with [alpha-32P]azidoanilido GTP was immunoblotted only by antibodies specific for the alpha-subunit of GQ-11. Thus V1 vascular AVP receptors of human platelets are coupled in a divalent cation-dependent manner to a G protein belonging to the Gq-11 family.
Department of Medicine, University Hospitals of Cleveland, Ohio.
M
M
Thibonnier
T
T
Goraya
L
L
Berti-Mattera
D001127:Arginine Vasopressin / Q000031:analogs & derivatives / Q000097:blood; D001345:Autoradiography; D001792:Blood Platelets / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D005033:Ethylmaleimide / Q000494:pharmacology; D020558:GTP Phosphohydrolases / Q000097:blood; D019204:GTP-Binding Proteins / Q000302:isolation & purification / Q000378:metabolism*; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000494:pharmacology; D006160:Guanosine Triphosphate / Q000097:blood*; D006801:Humans; D015151:Immunoblotting; D007700:Kinetics; D046911:Macromolecular Substances; D015636:Magnesium Chloride / Q000494:pharmacology; D010761:Phosphorus Radioisotopes; D017483:Receptors, Vasopressin / Q000187:drug effects / Q000302:isolation & purification / Q000378:metabolism*; D012969:Sodium Fluoride / Q000494:pharmacology
D046911:Macromolecular Substances; D010761:Phosphorus Radioisotopes; D017483:Receptors, Vasopressin; D015636:Magnesium Chloride; D001127:Arginine Vasopressin; D016244:Guanosine 5'-O-(3-Thiotriphosphate); C025043:vasopressin, 1-(1-mercaptocyclohexaneacetic acid)-2-(O- methyl-L-tyrosine)-8-L-arginine-; D006160:Guanosine Triphosphate; D012969:Sodium Fluoride; D020558:GTP Phosphohydrolases; D019204:GTP-Binding Proteins; D005033:Ethylmaleimide