The Role of Acidic Phospholipids in Glucagon Action on Rat Liver Adenylate Cyclase

摘要: Abstract We have examined the effects of phospholipase C from Bacillus cereus (Bc) and Clostridium perfringens (Cp) on various parameters involved in activity response adenylate cyclase to glucagon rat liver plasma membranes. A crude preparation Cp-phospholipase hydrolyzes "neutral" phospholipids (phosphatidylcholine, phosphatidylethanolamine, sphingomyelin) these In contrast, highly purified Bc-phospholipase acidic (phosphatidylserine, phosphatidylinositol) but not sphingomyelin. Treatment membranes with either type does alter basal or stimulatory fluoride ion enzyme system. abolishes whereas causes only partial loss even after hydrolysis 60% membrane phospholipids. These findings provide evidence that are more specifically activation cyclase. Acidic directly binding its receptor. results a 10-fold reduction affinity quantity specific sites for glucagon. Binding Des-His-glucagon, competitive, inactive analogue is unaffected by treatment displays same apparent as phospholipase-treated suggest liganding histidine residue regulatory site responsible action. GTP, which required action increases rate dissociation receptor, exert C-treated GTP also Des-His-glucagon untreated treated membranes, indicating be expressed. It appears, therefore, bind common both concerted at this site.