Interaction of the beta-adrenergic receptor with Gs following delipidation. Specific lipid requirements for Gs activation and GTPase function.
Preparations of beta-adrenergic receptor and Gs from turkey erythrocytes were delipidated by previously developed procedures. Three synthetic phospholipids, dioleoylglycerophosphoethanolamine, dioleoylglycerophosphocholine and dioleoylglycerophosphoserine plus an unphosphorylated lipid, were all required to restore receptor-mediated activation of Gs by GTP[gamma S]. The same lipids were necessary for the reconstitution of the isoproterenol-enhanced GTPase. The requirement for the unphosphorylated lipid could be fulfilled by 1-mono-oleoyl glycerol, alpha-tocopherol or oleic acid. Cholesterol hemisuccinate further enhanced the receptor-mediated activity of the relipidated system when present in addition to the lipids specified above. Cholesterol hemisuccinate had no effect on the basal rate of Gs activation and depressed the basal GTPase. It is therefore suggested that cholesterol hemisuccinate affects the receptor or the coupling of the receptor to Gs. In the system relipidated with the three dioleoyl phospholipids, plus alpha-tocopherol and cholesterol hemisuccinate, the initial rate of Gs activation per mole receptor appeared to be considerably higher than in the native turkey erythrocyte membrane.
Ben-Arie
N
N
Department of Biological Chemistry, Hebrew University of Jerusalem, Israel.
Gileadi
C
C
Schramm
M
M
D000818:Animals; D002788:Cholesterol Esters / Q000494:pharmacology; D004357:Drug Synergism; D004789:Enzyme Activation / Q000187:drug effects; D004910:Erythrocyte Membrane / Q000378:metabolism; D004912:Erythrocytes / Q000378:metabolism; D020558:GTP Phosphohydrolases / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000378:metabolism*; D007545:Isoproterenol / Q000494:pharmacology; D007700:Kinetics; D008055:Lipids / Q000494:pharmacology; D010743:Phospholipids / Q000378:metabolism* / Q000502:physiology; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism*; D010766:Phosphorylation; D011943:Receptors, Adrenergic, beta / Q000378:metabolism* / Q000502:physiology; D014422:Turkeys
D002788:Cholesterol Esters; D008055:Lipids; D010743:Phospholipids; D011943:Receptors, Adrenergic, beta; D010744:Phosphoric Monoester Hydrolases; D020558:GTP Phosphohydrolases; D019204:GTP-Binding Proteins; D007545:Isoproterenol; C013440:cholesteryl succinate