SPECTRIN AS A STABILIZER OF PHOSPHOLIPID ASYMMETRY IN HUMAN ERYTHROCYTE-MEMBRANE
SPECTRIN AS A STABILIZER OF PHOSPHOLIPID ASYMMETRY IN HUMAN ERYTHROCYTE-MEMBRANE
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DOI：
10.1016/0005-2736(78)90004-4
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发表时间：
1978-01-01
期刊：
影响因子：
--
通讯作者：
DEUTICKE, B
中科院分区：
文献类型：
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作者：
HAEST, CWM;PLASA, G;DEUTICKE, B
在用SH氧化剂(如四硫酸盐和联胺)处理完整的人红细胞后，磷脂酶A2能裂解大约30%的磷脂酰丝氨酸和50%的磷脂酰乙醇胺，而不会引起溶血。这些磷脂在新鲜的红细胞中几乎不被水解，被认为位于膜的内脂层。随着磷脂裂解的增强，膜上的SH基团减少了50%，位于膜内表面的光影蛋白与~lt；106道尔顿的低聚物发生了交联。用N-乙基马来酰亚胺封闭膜上约10%的SH基团，抑制了膜上光影蛋白的聚合，促进了磷脂的切割。在此条件下，N-乙基马来酰亚胺与3个SH基团的血影蛋白，0.7个SH基团的主要内在100，00道尔顿蛋白(带3)和1.1个SH基团的外源蛋白的72,000道尔顿(带4.2)。用碘乙酰胺阻断研究表明，100,000-道尔顿蛋白的SH基团不参与SH-氧化剂的作用。我们认为，释放血影蛋白的限制能使磷脂酰丝氨酸和磷脂酰乙醇胺从红细胞膜的内至外脂层移动，而在天然红细胞膜中，血影蛋白稳定了这些磷脂向膜内表面的定向。
After treatment of intact human erythrocytes with SH-oxidizing agents (e.g., tetrathionate and diamide), phospholipase A2 cleaves approximately 30% of the phosphatidylserine and 50% of the phosphatidylethanolamine without causing hemolysis. These phospholipids are scarcely hydrolyzed in fresh erythrocytes and are assumed to be located in the inner lipid layer of the membrane. The enhancement of the phospholipid cleavage was accompanied by a 50% decrease of the membrane SH-groups and a cross-linking of spectrin, located at the inner surface of the membrane, to oligomers of < 106 dalton. Blocking approximately 10% of the membrane SH groups with N-ethylmaleimide suppressed the polymerization of spectrin and the enhancement of the phospholipid cleavage. N-Ethylmaleimide, under these conditions, reacted with 3 SH groups per molecule of spectrin, 0.7 SH groups per major intrinsic 100,00 dalton protein (band 3) and 1.1 SH groups per molecule of an extrinsic protein of 72,000 daltons (band 4.2). Blocking studies with iodoacetamide demonstrate that the SH groups of the 100,000-dalton protein are not involved in the effects of the SH-oxidizing agents. It is suggested that a release of constraints imposed by spectrin enables phosphatidylserine and phosphatidylethanolamine to move from the inner to the outer lipid layer of the erythrocyte membrane and that spectrin, in the native erythrocyte, stabilizes the orientation of these phospholipids to the inner surface of the membrane.