Bruckdorfer K R, Crowe J, Sherry M K
Biochim Biophys Acta. 1984 Dec 19;778(3):489-96. doi: 10.1016/0005-2736(84)90398-5.
The mechanism of inter-membrane cholesterol exchange has been a matter of some debate. Evidence from kinetic studies indicates that cholesterol must transfer to and from membranes in a water-soluble form. In this study attempts have been made to demonstrate that this occurs using either dialysis membranes or a barrierless multiphase polymer system to physically separate the membranes. In both systems small amounts of cholesterol were seen to transfer from one membrane pool to another using both liposomes and erythrocyte membranes as donors or acceptors. The cholesterol transfer was shown to be independent of the movement of other membrane components. The amount of transfer observed was limited by the physical properties of the systems employed. The barrier to cholesterol transfer in the dialysis membrane system is primarily the pore size of the membrane, while in the multiphase polymer system the transfer was limited by the viscosity of the medium and the distance between the lower and upper phases containing the membranes. Nevertheless, the results provide evidence that cholesterol transfer is by a dissociation of molecules from membranes into the aqueous medium and does not require the formation of a collision complex between the membranes.
膜间胆固醇交换的机制一直存在一些争议。动力学研究的证据表明，胆固醇必须以水溶性形式进出膜。在本研究中，已尝试使用透析膜或无屏障多相聚合物系统来物理分离膜，以证明这种情况的发生。在这两个系统中，使用脂质体和红细胞膜作为供体或受体时，都观察到少量胆固醇从一个膜池转移到另一个膜池。胆固醇转移显示与其他膜成分的移动无关。观察到的转移量受到所用系统物理性质的限制。透析膜系统中胆固醇转移的障碍主要是膜的孔径，而在多相聚合物系统中，转移受到介质粘度以及含膜的上下相之间距离的限制。然而，结果提供了证据，表明胆固醇转移是通过分子从膜解离到水介质中，并且不需要膜之间形成碰撞复合物。
