Phospholipase A inhibition of opiate receptor binding can be reversed by albumin
Phospholipase A inhibition of opiate receptor binding can be reversed by albumin
复制标题
白蛋白可逆转磷脂酶 A 对阿片受体结合的抑制
作者：
Hung;E. J. Simon
动物和人脑中的阿片受体已被证明与细胞膜紧密相关1 -3。我们的实验室已经报道了埃托啡-受体复合物的增溶作用4，但迄今为止还不可能获得可溶形式的活性受体。尽管如此，它已经有可能研究膜结合受体的许多生化特性。它对巯基试剂和许多其他蛋白质试剂5，6以及蛋白水解酶1，7的敏感性表明蛋白质参与阿片结合。关于磷脂的功能，证据不太清楚。大鼠脑细胞膜制备物的阿片结合活性已被证明对蝰蛇毒液的磷脂酶A非常敏感（在ng ml−1范围内）8，但对响尾蛇毒液中存在的磷脂酶A或来自猪胰腺的磷脂酶A非常不敏感（Lin Simon，未发表）。磷脂酶C仅在非常高的浓度下具有抑制作用1，8。阿片受体的罗素蝰蛇酶和离子和非离子detergents 4，7点的极大敏感性磷脂在结合过程中可能发挥作用。我们在这里报告，抑制阿片类药物结合磷脂酶A可以逆转几乎完全由孵育的酶处理的膜与牛血清白蛋白（BSA）。
OPIATE receptors in animal and human brain have been shown to be tightly associated with cell membranes1–3. Our laboratory has reported the solubilisation of an etorphine–receptor complex4, but to date it has not been possible to obtain an active receptor in soluble form. Nevertheless, it has been possible to study many biochemical characteristics of the membrane-bound receptor. Its sensitivity to sulphhydryl reagents and a number of other protein reagents5,6 as well as to proteolytic enzymes1,7 suggests the participation of protein(s) in opiate binding. The evidence is less clear with respect to a function for phospholipids. Opiate binding activity of cell membrane preparations from rat brain has been shown to be exquisitely sensitive to phospholipase A of Vipera russelli venom (in the ng ml−1 range)8, but very insensitive to phospholipase A present in the venom of Crotalus adamenteus1 or that derived from pig pancreas (Lin & Simon, unpublished). Phospholipase C is inhibitory only in very high concentrations1,8. The great sensitivity of opiate receptors to the Russell's viper enzyme and to ionic and non-ionic detergents4,7 points to a possible role for phospholipids in the binding process. We report here that inhibition of opiate binding by phospholipase A can be reversed almost completely by incubation of the enzyme-treated membranes with bovine serum albumin (BSA).