LATERAL MOBILITY OF INTEGRAL PROTEINS IN RED-BLOOD-CELL TETHERS
LATERAL MOBILITY OF INTEGRAL PROTEINS IN RED-BLOOD-CELL TETHERS
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DOI：
10.1016/s0006-3495(92)81811-8
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发表时间：
1992-01-01
影响因子：
3.4
通讯作者：
HOCHMUTH, RM
中科院分区：
文献类型：
--
作者：
BERK, DA;HOCHMUTH, RM
红细胞膜是一种复杂的材料，既具有固体性质，又具有液体性质。它与简单的脂质双分子层胶囊的区别在于其机械性能，特别是其剪切粘弹性行为和整体蛋白质在膜表面的远距离迁移。当拉伸足够大时，膜失去剪切刚度，以二维流体的形式流动。这些实验研究了伴随拉伸破坏和液体状流动的机械现象的整体蛋白质迁移率的变化。一个流道装置被用来制造红细胞系索，这是一种中空的圆柱体，由变形很大的膜构成，长达36微米。利用光漂白后荧光再分布技术（FRAP）测量了膜表面蛋白质的扩散。整体膜蛋白直接用荧光素染料（DTAF）标记。通过光漂白一半的细胞并测量荧光恢复率来测量正常膜的迁移率。在整个系绳漂白后，根据荧光回收率计算系绳膜中的蛋白质迁移率。正常膜的荧光回收率表明，超过一半的标记蛋白是可移动的，扩散系数约为4 × 10(-11) cm2/s，与其他研究结果一致。蛋白质在系绳膜中的扩散系数大于1.5 × 10(-9) cm2/s。扩散系数的急剧增加表明拉伸破坏涉及脂质双分子层与膜骨架的分离。
The red blood cell membrane is a complex material that exhibits both solid- and liquidlike behavior. It is distinguished from a simple lipid bilayer capsule by its mechanical properties, particularly its shear viscoelastic behavior and by the long-range mobility of integral proteins on the membrane surface. Subject to sufficiently large extension, the membrane loses its shear rigidity and flows as a two-dimensional fluid. These experiments examine the change in integral protein mobility that accompanies the mechanical phenomenon of extensional failure and liquidlike flow. A flow channel apparatus is used to create red cell tethers, hollow cylinders of greatly deformed membrane, up to 36-mu-m long. The diffusion of proteins within the surface of the membrane is measured by the technique of fluorescence redistribution after photobleaching (FRAP). Integral membrane proteins are labeled directly with a fluorescein dye (DTAF). Mobility in normal membrane is measured by photobleaching half of the cell and measuring the rate of fluorescence recovery. Protein mobility in tether membrane is calculated from the fluorescence recovery rate after the entire tether has been bleached. Fluorescence recovery rates for normal membrane indicate that more than half the labeled proteins are mobile with a diffusion coefficient of approximately 4 x 10(-11) cm2/s, in agreement with results from other studies. The diffusion coefficient for proteins in tether membrane is greater than 1.5 x 10(-9) cm2/s. This dramatic increase in diffusion coefficient indicates that extensional failure involves the uncoupling of the lipid bilayer from the membrane skeleton.