Keller S L, Bezrukov S M, Gruner S M, Tate M W, Vodyanoy I, Parsegian V A
Department of Physics, Princeton University, New Jersey 08544.
Biophys J. 1993 Jul;65(1):23-7. doi: 10.1016/S0006-3495(93)81040-3.
With few exceptions, membrane lipids are usually regarded as a kind of filler or passive solvent for membrane proteins. Yet, cells exquisitely control membrane composition. Many phospholipids found in plasma membrane bilayers favor packing into inverted hexagonal bulk phases. It was suggested that the strain of forcing such lipids into a bilayer may affect membrane protein function, such as the operation of transmembrane channels. To investigate this, we have inserted the peptide alamethicin into bilayer membranes composed of lipids of empirically determined inverted hexagonal phase "spontaneous radii" Ro, which will have expectably different degrees of strain when forced into bilayer form. We observe a correlation between measured Ro and the relative probabilities of different conductance states. States of higher conductance are more probable in dioleoylphosphatidylethanolamine, the lipid of highest curvature, 1/Ro, than in dioleoylphosphatidylcholine, the lipid of lowest curvature.
除了少数例外情况，膜脂通常被视为膜蛋白的一种填充物或被动溶剂。然而，细胞能精确地控制膜的组成。质膜双层中发现的许多磷脂倾向于堆积成反相六角形本体相。有人提出，将此类脂质强行纳入双层结构所产生的张力可能会影响膜蛋白的功能，比如跨膜通道的运作。为了对此进行研究，我们将短杆菌肽插入由经验确定的反相六角形相“自发半径”Ro的脂质构成的双层膜中，当这些脂质被迫形成双层结构时，预计会有不同程度的张力。我们观察到测得的Ro与不同电导状态的相对概率之间存在相关性。在曲率最高的脂质二油酰磷脂酰乙醇胺（1/Ro）中，高电导状态比在曲率最低的脂质二油酰磷脂酰胆碱中更有可能出现。
