Armstrong Don L, Borchardt Dan B, Zidovetzki Raphael
Department of Cell Biology and Neuroscience, College of Natural and Agricultural Sciences, University of California, 1306/1303 Spieth, Riverside, CA 92521, USA.
Biochem Biophys Res Commun. 2002 Aug 30;296(4):806-12. doi: 10.1016/s0006-291x(02)00946-4.
The perturbations induced by second messenger diacylglycerols (DAGs) into bovine brain phosphatidylcholine (BBPC) bilayers in the presence or absence of bovine brain sphingomyelin (SM) and/or cholesterol were studied by (2)H NMR. Addition of 15 mol% DAG to BBPC bilayers did not induce non-bilayer lipid phases in the temperature range 30-60 degrees C. Similar measurements performed in the presence of cholesterol revealed that cholesterol progressively destabilizes PC bilayers with respect to DAG-induced perturbations. Thus, at 40 mol% cholesterol, addition of 15 mol% DAG induced the formation of non-bilayer (isotropic and inverted hexagonal) phases at 60 degrees C. Whereas some lateral separation of the bilayers into domains of different cholesterol contents was observed in BBPC/cholesterol membranes, such a lateral heterogeneity was greatly facilitated by the addition of SM. Since both a tendency to form non-bilayer lipid phases and lateral heterogeneity of the membranes are associated with increased activation of a number of membrane-associated enzymes, our results suggest that SM- and cholesterol-enriched regions of biological membranes (rafts) provide an environment with increased sensitivity to the generation of lipid second messengers and modified transmembrane signal transduction properties.
通过（2）H NMR研究了在存在或不存在牛脑鞘磷脂（SM）和/或胆固醇的情况下，第二信使二酰基甘油（DAG）对牛脑磷脂酰胆碱（BBPC）双层膜的扰动。在30-60摄氏度的温度范围内，向BBPC双层膜中添加15摩尔％的DAG不会诱导非双层脂质相。在胆固醇存在下进行的类似测量表明，相对于DAG诱导的扰动，胆固醇会逐渐使PC双层膜不稳定。因此，在40摩尔％的胆固醇下，添加15摩尔％的DAG会在60摄氏度时诱导形成非双层（各向同性和反相六角形）相。虽然在BBPC/胆固醇膜中观察到双层膜横向分离成不同胆固醇含量的区域，但添加SM极大地促进了这种横向异质性。由于形成非双层脂质相的趋势和膜的横向异质性都与许多膜相关酶的活化增加有关，我们的结果表明，生物膜（筏）中富含SM和胆固醇的区域提供了一个对脂质第二信使的产生和修饰的跨膜信号转导特性更敏感的环境。
