The coupling of pertussis toxin-sensitive G proteins to phospholipase A2 and adenylyl cyclase in CHO cells expressing bovine rhodopsin.
The regulation of phospholipase A2 by G protein-coupled receptors is examined in CHO cells which normally express the purinergic receptor and have been transfected with bovine rhodopsin. The purinergic receptor has been reported to activate both phospholipase C and phospholipase A2 in this cell line. In contrast, bovine rhodopsin by itself is not able to activate phospholipase A2. However, the photoreceptor does potentiate purinergic receptor-mediated phospholipase A2 activation in a light-dependent manner. Both the purinergic receptor stimulation of phospholipase A2 and the enhanced activity mediated by rhodopsin are completely pertussis toxin-sensitive, suggesting the regulation of phospholipase A2 by a member of the Gi family of G proteins. Both of these receptors also inhibit adenylyl cyclase activity. Rhodopsin-mediated inhibition of adenylyl cyclase is pertussis toxin-sensitive, whereas inhibition by the purinergic receptor is calcium-sensitive but not pertussis toxin-sensitive. These results suggest (1) that rhodopsin is similar to other receptors that normally couple to Gi when expressed in cultured cells and (2) that regulation of adenylyl cyclase and PLA2 in CHO cells by rhodopsin and the purinergic receptor occur via distinct pathways.
Dickerson
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CD
Department of Cell Biology and Anatomy, University of North Carolina at Chapel Hill 27599.
Weiss
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D000255:Adenosine Triphosphate / Q000494:pharmacology; D037361:Adenylate Cyclase Toxin; D000067956:Adenylyl Cyclase Inhibitors; D000262:Adenylyl Cyclases / Q000378:metabolism*; D000470:Alkaloids / Q000494:pharmacology; D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism; D016466:CHO Cells / Q000201:enzymology; D002118:Calcium / Q000378:metabolism; D002417:Cattle; D006224:Cricetinae; D004789:Enzyme Activation / Q000187:drug effects; D019204:GTP-Binding Proteins / Q000502:physiology*; D008027:Light; D037342:Pertussis Toxin; D010741:Phospholipases A / Q000037:antagonists & inhibitors / Q000378:metabolism*; D054467:Phospholipases A2; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D011953:Receptors, Cyclic AMP / Q000502:physiology*; D012243:Rhodopsin / Q000502:physiology*; D019311:Staurosporine; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D037361:Adenylate Cyclase Toxin; D000067956:Adenylyl Cyclase Inhibitors; D000470:Alkaloids; D011953:Receptors, Cyclic AMP; D010566:Virulence Factors, Bordetella; D016718:Arachidonic Acid; D000255:Adenosine Triphosphate; D012243:Rhodopsin; D037342:Pertussis Toxin; D011493:Protein Kinase C; D010741:Phospholipases A; D054467:Phospholipases A2; D019204:GTP-Binding Proteins; D000262:Adenylyl Cyclases; D019311:Staurosporine; D002118:Calcium