Fahrenholz F, Klein U, Gimpl G
Max-Planck-Institute of Biophysics, Frankfurt am Main, Germany.
Adv Exp Med Biol. 1995;395:311-9.
Reconstitution experiments with the myometrial oxytocin receptor from guinea pig showed a strong requirement of the oxytocin receptor binding function for the presence of cholesterol in preformed liposomes. To investigate the effect of cholesterol on the oxytocin receptor in the plasma membrane, a new method to modify the membrane cholesterol content was developed. With substituted cyclodextrins we were able to selectively deplete the myometrial plasma membrane of cholesterol. Vice versa, incubation of cholesterol-depleted membranes with a soluble cholesterol cyclodextrin complex restored the cholesterol content of the plasma membrane. Binding experiments showed, that with the removal of cholesterol from the membrane, the oxytocin receptor was converted from high to low affinity state. Increasing the cholesterol content of the membrane again restored the high binding affinity. Substitution of membrane cholesterol with other steroids showed a strong dependence of the oxytocin receptor function on the structure of the cholesterol molecule. Experiments with the detergent solubilized oxytocin receptor and with oxytocin receptors expressed in the Baculovirus/Sf9 cell system provided further evidence for a direct interaction of the oxytocin receptor with cholesterol.
对豚鼠子宫肌层催产素受体进行的重组实验表明，预先形成的脂质体中胆固醇的存在对催产素受体结合功能有强烈需求。为了研究胆固醇对质膜中催产素受体的影响，开发了一种改变膜胆固醇含量的新方法。利用取代环糊精，我们能够选择性地耗尽子宫肌层质膜中的胆固醇。反之，用可溶性胆固醇环糊精复合物孵育耗尽胆固醇的膜可恢复质膜的胆固醇含量。结合实验表明，随着膜中胆固醇的去除，催产素受体从高亲和力状态转变为低亲和力状态。再次增加膜中的胆固醇含量可恢复高结合亲和力。用其他类固醇取代膜胆固醇表明，催产素受体功能强烈依赖于胆固醇分子的结构。用去污剂溶解的催产素受体以及在杆状病毒/Sf9细胞系统中表达的催产素受体进行的实验为催产素受体与胆固醇的直接相互作用提供了进一步证据。
