Lateral Diffusion of Membrane Proteins
Lateral Diffusion of Membrane Proteins
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DOI：
10.1021/ja902853g
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发表时间：
2009-09-09
影响因子：
15
通讯作者：
Poolman, Bert
中科院分区：
文献类型：
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作者：
Ramadurai, Sivaramakrishnan;Holt, Andrea;Poolman, Bert
我们测量的横向流动性的整体膜蛋白重建在巨大的单层囊泡（GUV），使用荧光相关光谱。荧光标记具有1-36个跨膜区段（横向半径范围为0.5至4 nm）和α-螺旋肽（半径为0.5nm）的受体、通道和转运蛋白并将其掺入GUV中。在低蛋白质-脂质比（即，每μ m（2）膜表面10-100个蛋白质），扩散系数D对蛋白质的流体动力学半径（R）表现出较弱的依赖性[D与In（1/R）成比例]，与Saffman-Delbruck模型一致。在较高的蛋白质与脂质的比例（高达3000 μ m（-2）），分子的横向扩散系数随膜中蛋白质浓度的增加而线性下降。我们的研究结果的影响，在生物膜中的蛋白质流动性（蛋白质拥挤类似于25,000 μ m（-2））和使用扩散测量蛋白质的几何形状（大小，寡聚化）的测定进行了讨论。
We measured the lateral mobility of integral membrane proteins reconstituted in giant unilamellar vesicles (GUVs), using fluorescence correlation spectroscopy. Receptor, channel, and transporter proteins with 1-36 transmembrane segments (lateral radii ranging from 0.5 to 4 nm) and a alpha-helical peptide (radius of 0.5 nm) were fluorescently labeled and incorporated into GUVs. At low protein-to-lipid ratios (i.e., 10-100 proteins per mu m(2) of membrane surface), the diffusion coefficient D displayed a weak dependence on the hydrodynamic radius (R) of the proteins [D scaled with In(1/R)], consistent with the Saffman-Delbruck model. At higher protein-to lipid ratios (up to 3000 mu m(-2)), the lateral diffusion coefficient of the molecules decreased linearly with increasing the protein concentration in the membrane. The implications of our findings for protein mobility in biological membranes (protein crowding of similar to 25,000 mu m(-2)) and use of diffusion measurements for protein geometry (size, oligomerization) determinations are discussed.