Interaction of the β‐adrenergic receptor with Gs following delipidation

Abstract

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-mediate 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-monooleoyl 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 phospolipids, plus .alpha.-tocopherol and cholesterol hemissucinate, the initial rate of Gs activation per mole receptor appeared to be considerably higher than in the native turkey erythrocyte membrane.