Abstract
G-protein-coupled receptors of the rhodopsin family transduce many important neural and endocrine signals. These receptors activate heterotrimeric G proteins and in many cases also cause activation of phospholipase D, an enzyme that can be controlled by the small G proteins ARF and RhoA. Here we show that the activation of phospholipase D that is induced by many, but not all, Ca2+-mobilizing G-protein-coupled receptors is sensitive to inhibitors of ARF and of RhoA. Receptors of this type were co-immunoprecipitated with ARF or RhoA on exposure to agonists, and the effects of GTP analogues on ligand binding to the receptor changed to a profile that is characteristic of small G proteins. These receptors contain the amino-acid sequence AsnProXXTyr in their seventh transmembrane domain, whereas receptors capable of activating phospholipase D without involving ARF contain the sequence AspProXXTyr. Mutation of this latter sequence to AsnProXXTyr in the gonadotropin-releasing hormone receptor conferred sensitivity to an inhibitor of ARF, and the reciprocal mutation in the 5-HT2A receptor for 5-hydroxy-tryptamine reduced its sensitivity to the inhibitor. Receptors carrying the AsnProXXTyr motif thus seem to form functional complexes with ARF and RhoA.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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ADP-Ribosylation Factors
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Animals
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Brefeldin A
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COS Cells
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Cyclopentanes / pharmacology
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Enzyme Activation
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Estrenes / pharmacology
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GTP-Binding Proteins / antagonists & inhibitors
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GTP-Binding Proteins / metabolism*
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Guanosine Triphosphate / analogs & derivatives
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Guanosine Triphosphate / metabolism
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Humans
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Male
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Phospholipase D / antagonists & inhibitors
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Phospholipase D / metabolism*
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Pyrrolidinones / pharmacology
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Rats
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Receptor, Muscarinic M3
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Receptors, LHRH / agonists
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Receptors, LHRH / chemistry
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Receptors, LHRH / genetics
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Receptors, LHRH / metabolism*
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Receptors, Muscarinic / chemistry
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Receptors, Muscarinic / metabolism*
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Recombinant Proteins / metabolism
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Rhodopsin / chemistry
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Rhodopsin / metabolism*
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Tumor Cells, Cultured
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Type C Phospholipases / antagonists & inhibitors
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Type C Phospholipases / metabolism
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rhoA GTP-Binding Protein
Substances
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Cyclopentanes
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Estrenes
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Pyrrolidinones
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Receptor, Muscarinic M3
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Receptors, LHRH
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Receptors, Muscarinic
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Recombinant Proteins
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1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione
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Brefeldin A
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Guanosine Triphosphate
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Rhodopsin
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Type C Phospholipases
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Phospholipase D
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GTP-Binding Proteins
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ADP-Ribosylation Factors
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rhoA GTP-Binding Protein