INTERACTIONS BETWEEN SATURATED ACYL CHAINS CONFER DETERGENT RESISTANCE ON LIPIDS AND GLYCOSYLPHOSPHATIDYLINOSITOL (GPI)-ANCHORED PROTEINS - GPI-ANCHORED PROTEINS IN LIPOSOMES AND CELLS SHOW SIMILAR BEHAVIOR
INTERACTIONS BETWEEN SATURATED ACYL CHAINS CONFER DETERGENT RESISTANCE ON LIPIDS AND GLYCOSYLPHOSPHATIDYLINOSITOL (GPI)-ANCHORED PROTEINS - GPI-ANCHORED PROTEINS IN LIPOSOMES AND CELLS SHOW SIMILAR BEHAVIOR
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DOI：
10.1073/pnas.91.25.12130
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发表时间：
1994-12-06
影响因子：
11.1
通讯作者：
BROWN, D
中科院分区：
文献类型：
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作者：
SCHROEDER, R;LONDON, E;BROWN, D
由GPI锚定的蛋白质与冷非离子洗涤剂从细胞膜中溶解很差，因为它们与富含胆固醇和鞘脂的耐洗涤剂耐药膜相关。在这项研究中，我们证明了胆固醇和富含鞘脂的脂质体并未完全通过Triton X-100溶解。在这些脂质体中掺入的GPI锚定的胎盘碱性磷酸酶也未被冷的Triton X-100溶解。由于鞘脂与细胞磷脂的熔融温度（T-M）高得多，因此与T-M相关的特性可能会导致清洁剂的提取性。为了支持这一想法，我们发现Triton X-100有效地从耐洗涤剂的脂质体中有效提取了低-T-M脂质二酰磷脂酰胆碱（DOPC），而High-T-M Lipid Dipalmitylmitylmitylmitylmityl磷脂酰胆碱（DPPC）却没有。测量了脂质体掺入的二苯基甲酰二苯乙烯的荧光极化，以确定耐洗涤剂脂质体的“流动性”。我们发现这些脂质体与DPPC/胆固醇脂质体一样的流体，这些脂质体在液体级相处的流体，液体的液体比DOPC或DOPC或DOPC/胆固醇脂质体少得多。这些发现可能解释了GPI锚定蛋白的行为，该蛋白通常具有饱和的脂肪酰基链，并且应该偏爱较低的荧光膜。因此，我们提出酰基链相互作用会影响GPI锚定蛋白与耐洗涤剂膜脂质的关联。 GPI锚定蛋白与不在液晶状态的富含鞘脂的膜相的亲和力对于确定其细胞定位可能很重要。
Proteins anchored by GPI are poorly solubilized from cell membranes by cold nonionic detergents because they associate with detergent-resistant membranes rich in cholesterol and sphingolipids. In this study, we demonstrated that cholesterol and sphingolipid-rich liposomes were incompletely solubilized by Triton X-100. GPI-anchored placental alkaline phosphatase incorporated in these liposomes was also not solubilized by cold Triton X-100. As sphingolipids have much higher melting temperatures (T-m) than cellular phospholipids, a property correlated with T-m might cause detergent inextractability. In support of this idea, we found that the low-T-m lipid dioleoyl phosphatidylcholine (DOPC) was efficiently extracted from detergent-resistant liposomes by Triton X-100, whereas the high-T-m lipid dipalmitoyl phosphatidylcholine (DPPC) was not. The fluorescence polarization of liposome-incorporated diphenylhexatriene was measured to determine the ''fluidity'' of the detergent-resistant liposomes. We found that these liposomes were about as fluid as DPPC/cholesterol liposomes, which were present in the liquid-ordered phase, and much less fluid than DOPC or DOPC/cholesterol liposomes. These findings may explain the behavior of GPI-anchored proteins, which often have saturated fatty acyl chains and should prefer a less-fluid membrane. Therefore, we propose that acyl chain interactions can influence the association of GPI-anchored proteins with detergent-resistant membrane lipids. The affinity of GPI-anchored proteins for a sphingolipid-rich membrane phase that is not in the liquid crystalline state may be important in determining their cellular localization.