We consider a model lipid plasma membrane, one that describes the outer leaf as consisting of sphingomyelin, phosphatidylcholine, and cholesterol and the inner leaf of phosphatidylethanolamine, phosphatidylserine, phosphatidylcholine, and cholesterol. Their relative compositions are taken from experiment; the cholesterol freely interchanges between leaves. Fluctuations in local composition are coupled to fluctuations in the local membrane curvature, as in the Leibler-Andelman mechanism. Structure factors of components in both leaves display a peak at nonzero wavevector. This indicates that the disordered fluid membrane is characterized by structure of the corresponding wavelength. The scale is given by membrane properties: its bending modulus and its surface tension, which arises from the membrane's connections to the cytoskeleton. From measurements on the plasma membrane, this scale is on the order of 100 nm. We find that the membrane can be divided into two different kinds of domains that differ not only in their composition but also in their curvature. The first domain in the outer, exoplasmic leaf is rich in cholesterol and sphingomyelin, whereas the inner, cytoplasmic leaf is rich in phosphatidylserine and phosphatidylcholine. The second kind of domain is rich in phosphatidylcholine in the outer leaf and in cholesterol and phosphatidylethanolamine in the inner leaf. The theory provides a tenable basis for the origin of structure in the plasma membrane and an illuminating picture of the organization of lipids therein.

中文翻译：

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模型等离子膜在两片叶子中都表现出微乳液，为“筏”提供了基础

我们考虑一种模型脂质质膜，该膜将外叶描述为由鞘磷脂、磷脂酰胆碱和胆固醇组成，而内叶由磷脂酰乙醇胺、磷脂酰丝氨酸、磷脂酰胆碱和胆固醇组成。它们的相对成分取自实验；胆固醇在叶子之间自由交换。局部成分的波动与局部膜曲率的波动有关，如 Leibler-Andelman 机制。两片叶中成分的结构因子在非零波矢处显示一个峰值。这表明无序流体膜具有相应波长的结构特征。尺度是由膜特性给出的：它的弯曲模量和它的表面张力，这是由膜与细胞骨架的连接引起的。从对质膜的测量来看，这个尺度在 100 nm 的数量级。我们发现膜可以分为两种不同的域，它们不仅在组成上不同，而且在曲率上也不同。外质叶的第一个结构域富含胆固醇和鞘磷脂，而内细胞质叶富含磷脂酰丝氨酸和磷脂酰胆碱。第二种结构域的外叶富含磷脂酰胆碱，内叶富含胆固醇和磷脂酰乙醇胺。该理论为质膜结构的起源和其中脂质组织的阐明提供了可靠的基础。我们发现膜可以分为两种不同的域，它们不仅在组成上不同，而且在曲率上也不同。外质叶的第一个结构域富含胆固醇和鞘磷脂，而内细胞质叶富含磷脂酰丝氨酸和磷脂酰胆碱。第二种结构域的外叶富含磷脂酰胆碱，内叶富含胆固醇和磷脂酰乙醇胺。该理论为质膜结构的起源和其中脂质组织的阐明提供了可靠的基础。我们发现膜可以分为两种不同的域，它们不仅在组成上不同，而且在曲率上也不同。外质叶的第一个结构域富含胆固醇和鞘磷脂，而内细胞质叶富含磷脂酰丝氨酸和磷脂酰胆碱。第二种结构域的外叶富含磷脂酰胆碱，内叶富含胆固醇和磷脂酰乙醇胺。该理论为质膜结构的起源和其中脂质组织的阐明提供了可靠的基础。胞质叶富含磷脂酰丝氨酸和磷脂酰胆碱。第二种结构域的外叶富含磷脂酰胆碱，内叶富含胆固醇和磷脂酰乙醇胺。该理论为质膜结构的起源和其中脂质组织的阐明提供了可靠的基础。胞质叶富含磷脂酰丝氨酸和磷脂酰胆碱。第二种结构域的外叶富含磷脂酰胆碱，内叶富含胆固醇和磷脂酰乙醇胺。该理论为质膜结构的起源和其中脂质组织的阐明提供了可靠的基础。