Ordered and disordered phases coexist in plasma membrane vesicles of RBL-2H3 mast cells. An ESR study
Ordered and disordered phases coexist in plasma membrane vesicles of RBL-2H3 mast cells. An ESR study
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DOI：
10.1016/s0006-3495(03)74563-9
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发表时间：
2003-08-01
影响因子：
3.4
通讯作者：
Freed, JH
中科院分区：
文献类型：
--
作者：
Ge, MT;Gidwani, A;Freed, JH
用四种链自旋标记物和一种自旋标记的胆甾烷研究了22 ℃ ~ 45 ℃温度范围内RBL-2 H3肥大细胞质膜囊泡的动态结构。分析表明，大多数标记物的光谱由两个组分组成。丰富的光谱成分表现出大量的有序性，这是一个液晶有序（Lo）相，和模型膜所代表的液晶（Lc）相之间的中间。此外，旋转扩散速率的自旋标签是那些在Lo阶段。相比之下，丰度较低的组分的排序要低得多。这些结果表明，LO样区域或相（丰富的组分）和LC样区域或相（较不丰富的组分）共存于PMV中。相反，从提取的脂质重构的膜仅表现出更有序的相。这表明，膜相关蛋白是重要的共存的LO样和LC样区域在质膜。此外，豆蔻酰化的蛋白质，ARF 6的PMV的结合，导致一个新的光谱成分的头基脂质自旋标记，表明质膜缺陷的形成，这种低分子量的GTdR。
Four chain spin labels and a spin-labeled cholestane were used to study the dynamic structure of plasma membrane vesicles (PMV) prepared from RBL-2H3 mast cells at temperatures ranging from 22degreesC to 45degreesC. Analysis shows that the spectra from most labels consist of two components. The abundant spectral components exhibit substantial ordering that is intermediate between that of a liquid-ordered (Lo) phase, and that of a liquid-crystalline (Lc) phase as represented by model membranes. Also, rotational diffusion rates of the spin labels are comparable to those in the Lo phase. In contrast, the ordering for the less abundant components is much lower. These results indicate that a Lo-like region or phase ( the abundant component) and an Lc-like region or phase ( the less abundant component) coexist in the PMV. In contrast, membranes reconstituted from extracted lipids exhibit the more ordered phase only. This suggests that membrane-associated proteins are important for the coexistence of Lo-like and Lc-like regions in the plasma membrane. In addition, binding of the myristoylated protein, ARF6 to PMV, leads to a new spectral component for a headgroup lipid spin label that indicates the formation of plasma membrane defects by this low molecular weight GTPase.