Chong P L
Department of Biochemistry, Temple University School of Medicine, Philadelphia, PA 19140.
Proc Natl Acad Sci U S A. 1994 Oct 11;91(21):10069-73. doi: 10.1073/pnas.91.21.10069.
To investigate the lateral organization of sterols in membranes, the fluorescence intensity of dehydroergosterol at different mole fractions in liquid crystalline dimyristoyl phosphatidylcholine bilayers was examined. A number of intensity drops were observed at specific mole fractions, as predicted from a hexagonal super-lattice model. The fluorescence dips provide compelling evidence that a naturally occurring sterol is regularly distributed at fixed compositional fractions, consistent with the presence of hexagonal super-lattices in the fluid membranes. Regularly distributed regions, however, coexist with irregularly distributed regions. The extent of regular distribution varies periodically with sterol mole fraction and, consequently, similar variations take place in the membrane volume and lipid packing. This level of modulation in local membrane structure by minute changes in sterol concentration should have profound implications for the functional role of cholesterol content in cell membranes.
为了研究膜中甾醇的侧向组织，检测了液晶态二肉豆蔻酰磷脂酰胆碱双层膜中不同摩尔分数的脱氢麦角固醇的荧光强度。正如从六边形超晶格模型预测的那样，在特定摩尔分数处观察到了多个强度下降。荧光下降提供了有力证据，表明天然存在的甾醇以固定的组成分数规则分布，这与流体膜中六边形超晶格的存在一致。然而，规则分布的区域与不规则分布的区域共存。规则分布的程度随甾醇摩尔分数周期性变化，因此膜体积和脂质堆积也发生类似变化。甾醇浓度的微小变化对局部膜结构的这种调节水平应该对细胞膜中胆固醇含量的功能作用具有深远影响。
