Dynamics of putative raft-associated proteins at the cell surface.
Dynamics of putative raft-associated proteins at the cell surface.
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DOI：
10.1083/jcb.200312170
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发表时间：
2004-06-07
影响因子：
7.8
通讯作者：
Lippincott-Schwartz, Jennifer
中科院分区：
文献类型：
--
作者：
Kenworthy, Anne K;Nichols, Benjamin J;Remmert, Catha L;Hendrix, Glenn M;Kumar, Mukesh;Zimmerberg, Joshua;Lippincott-Schwartz, Jennifer
脂筏被概念化为富含胆固醇和鞘糖脂的膜微区，其充当蛋白分离和信号传导的平台。这些结构域在体内的性质尚不清楚。在这里，我们使用光漂白后的荧光恢复来测试筏协会是否影响蛋白质的能力，横向扩散大的距离在细胞表面。在稳态条件下和响应筏扰动的几种类型的假定筏和非筏蛋白质的扩散系数（D）进行了系统的测量。筏蛋白在大距离（>4 μm）上自由扩散，显示出10倍变化的Ds。这一发现表明，筏蛋白不进行远程扩散的离散，稳定的筏域的一部分。扰动影响模型膜系统中的脂筏或生化分馏（胆固醇耗尽，降低温度，胆固醇负荷）有类似的影响筏和nonraft蛋白的扩散流动性。因此，筏协会是不是在确定在细胞表面的长距离蛋白质的流动性的主导因素。
Lipid rafts are conceptualized as membrane microdomains enriched in cholesterol and glycosphingolipid that serve as platforms for protein segregation and signaling. The properties of these domains in vivo are unclear. Here, we use fluorescence recovery after photobleaching to test if raft association affects a protein's ability to laterally diffuse large distances across the cell surface. The diffusion coefficients (D) of several types of putative raft and nonraft proteins were systematically measured under steady-state conditions and in response to raft perturbations. Raft proteins diffused freely over large distances (>4 μm), exhibiting Ds that varied 10-fold. This finding indicates that raft proteins do not undergo long-range diffusion as part of discrete, stable raft domains. Perturbations reported to affect lipid rafts in model membrane systems or by biochemical fractionation (cholesterol depletion, decreased temperature, and cholesterol loading) had similar effects on the diffusional mobility of raft and nonraft proteins. Thus, raft association is not the dominant factor in determining long-range protein mobility at the cell surface.