The curvature and cholesterol content of phospholipid bilayers alter the transbilayer distribution of specific molecular species of phosphatidylethanolamine.
The curvature and cholesterol content of phospholipid bilayers alter the transbilayer distribution of specific molecular species of phosphatidylethanolamine.
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磷脂双层的曲率和胆固醇含量改变了磷脂酰乙醇胺特定分子种类的跨双层分布。
DOI：
10.1080/09687680050197383
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发表时间：
2000
期刊：
影响因子：
--
通讯作者：
Jenski,LJ
中科院分区：
文献类型：
--
作者：
Williams,EE;Cooper,JA;Stillwell,W;Jenski,LJ
磷脂的曲率、胆固醇含量和跨双层分布显著影响细胞膜的功能特性，但对这些参数如何相互作用知之甚少。在这项研究中，磷脂酰乙醇胺（PE）的transbilayer分布的囊泡与大（98 nm）和小（19 nm）的曲率半径和不同比例的PE，磷脂酰胆碱，和胆固醇。结果发现，这两种类型的囊泡的平均直径不受其脂质组成的影响，并且氨基反应性化合物2，4，6-三硝基苯磺酸（TNBS）无法穿过任何类型的囊泡的双层。当用TNBS处理大囊泡时，约40%的总膜PE被衍生化;在小囊泡中，55%发生反应。这些值被解释为代表存在于囊泡双层的外小叶中的总膜PE的百分比。大囊泡可能含有约20%的总膜脂质作为内膜。因此，在两种类型的囊泡中，PE作为磷脂类随机分布在双层的内外小叶之间。外叶中总PE的比例不受囊泡胆固醇或PE含量变化的影响。然而，跨双层分布的个别分子种类的PE不是随机的，并显着影响曲率半径，膜胆固醇含量，或两者兼而有之。例如，棕榈酸酯和二十二碳六烯酸的PE物种优先位于双层的外叶。膜胆固醇含量的影响transbilayer分布的硬脂酸酯，油酸酯，和亚麻酸含物种。棕榈酸酯，二十二碳六烯酸酯，硬脂酸酯的跨双层分布的物种显着影响膜曲率，但只有在存在高水平的胆固醇。因此，膜曲率和胆固醇含量的差异改变了磷脂双层表面上存在的PE分子的阵列。在细胞和细胞器中，这些差异可能对许多关键的膜功能和过程产生深远的影响。
The curvature, cholesterol content,and transbilayer distribution of phospholipids significantly influence the functional properties of cellular membranes, yet little is known of how these parameters interact. In this study, the transbilayer distribution of phosphatidylethanolamine (PE) is determined in vesicles with large (98 nm) and small (19 nm)radii of curvature and with different proportions of PE, phosphatidylcholine, and cholesterol. It was found that the mean diameters of both types of vesicles were not influenced by their lipid composition, and that the amino-reactive compound 2,4,6-trinitrobenzenesulphonic acid (TNBS) was unable to cross the bilayer of either type of vesicle. When large vesicles were treated with TNBS, ~40% of the total membrane PE was derivatized; in the small vesicles 55% reacted. These values are interpreted as representing the percentage of total membrane PE residing in the outer leaflet of the vesicle bilayer. The large vesicles likely contained ~20% of the total membrane lipid as internal membranes. Therefore, in both types of vesicles, PE as a phospholipid class was randomly distributed between the inner and outer leaflets ofthe bilayer. The proportion oftotal PE residing in the outer leaflet was unaffected by changes in either the cholesterol orPE content of the vesicles. However, the transbilayer distributions of individual molecular species of PE were not random, and were significantly influenced by radius of curvature, membrane cholesterol content, or both. For example, palmitate and docosahexaenoate-containing species of PE were preferentially located in the outer leaflet of the bilayer. Membrane cholesterol content affected the transbilayer distributions of stearate-, oleate-, and linoleate-containing species. The transbilayer distributions ofpalmitate-, docosahexaenoate-, and stearate-containing species were significantly influenced by membrane curvature, but only in the presence of high levels of cholesterol. Thus, differences in membrane curvature and cholesterol content alter the array of PE molecules present on the surfaces of phospholipid bilayers. In cells and organelles, these differences could have profound effects on a number of critical membrane functions and processes.