TY - JOUR
T1 - The G protein coupled to the thromboxane A2 receptor in human platelets is a member of the novel Gq family
AU - Shenker, Andrew
AU - Goldsmith, Paul
AU - Unson, Cecilia G.
AU - Spiegel, Allen M.
N1 - Copyright:
Copyright 2007 Elsevier B.V., All rights reserved.
PY - 1991
Y1 - 1991
N2 - The thromboxane A2 (TXA2) receptor in human platelets is coupled to a pertussis toxin-insensitive G protein whose identity has remained unknown. Candidates for this role include the atypical G protein known as Gz and members of a recently discovered G protein family known as Gq. Because of the proven utility of antibodies directed against the C terminus of G protein α subunits as functional probes, we prepared an antibody against a synthetic decapeptide corresponding to the C-terminal sequence shared by an and αq, two members of the new family. This antibody (QL) does not recognize known a subunits but selectively binds to a 42-kDa protein in a variety of tissues, including human platelet membranes. QL and two other C-terminal antibodies, QN and AS, known to recognize αz and αi2, respectively, were tested for their ability to block agonist-stimulated GTPase activity in human platelet membranes. Pretreatment of platelet membranes with AS has previously been shown to interfere with α2 adrenergic receptor-mediated inhibition of adenylylcyclase. As expected, only AS antibody produced inhibition of α2 receptor-stimulated GTPase. Pretreatment of membranes with QL, but not QN or AS, caused marked inhibition of TXA2 receptor-stimulated GTPase. This identifies the G protein coupled to human platelet TXAz receptors as a member of the novel Gq family.
AB - The thromboxane A2 (TXA2) receptor in human platelets is coupled to a pertussis toxin-insensitive G protein whose identity has remained unknown. Candidates for this role include the atypical G protein known as Gz and members of a recently discovered G protein family known as Gq. Because of the proven utility of antibodies directed against the C terminus of G protein α subunits as functional probes, we prepared an antibody against a synthetic decapeptide corresponding to the C-terminal sequence shared by an and αq, two members of the new family. This antibody (QL) does not recognize known a subunits but selectively binds to a 42-kDa protein in a variety of tissues, including human platelet membranes. QL and two other C-terminal antibodies, QN and AS, known to recognize αz and αi2, respectively, were tested for their ability to block agonist-stimulated GTPase activity in human platelet membranes. Pretreatment of platelet membranes with AS has previously been shown to interfere with α2 adrenergic receptor-mediated inhibition of adenylylcyclase. As expected, only AS antibody produced inhibition of α2 receptor-stimulated GTPase. Pretreatment of membranes with QL, but not QN or AS, caused marked inhibition of TXA2 receptor-stimulated GTPase. This identifies the G protein coupled to human platelet TXAz receptors as a member of the novel Gq family.
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M3 - Article
C2 - 1851174
AN - SCOPUS:0025880172
SN - 0021-9258
VL - 266
SP - 9309
EP - 9313
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 14
ER -