Translational diffusion of individual class II MHC membrane proteins in cells
Translational diffusion of individual class II MHC membrane proteins in cells
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DOI：
10.1016/s0006-3495(02)75277-6
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发表时间：
2002-11-01
影响因子：
3.4
通讯作者：
McConnell, HM
中科院分区：
文献类型：
--
作者：
Vrljic, M;Nishimura, SY;McConnell, HM
采用单分子荧光显微镜观察gpi连接和天然I-E-k类II MHC膜蛋白在CHO细胞质膜中的平移运动。这项研究的目的是寻找可能由运动障碍引起的布朗扩散的偏差。洗涤剂萃取表明这些蛋白质可能局限于脂质微域；在质膜中。单个I-E-k蛋白用cy5标记的肽可视化，该肽与两种蛋白共同的特定胞质外位点结合。单分子轨迹用于计算位移的径向分布，得到的平均扩散系数为0.22 （gpi链接的I-E-k）和0.18 mum(2)/s（原生I-E-k）。在分子间分离的0.3-1.0 μ m范围内，还研究了蛋白质对的相对扩散，以区分蛋白质分子的自由扩散和蛋白质在快速扩散的小区域内的扩散。两种分析都表明，运动主要是布朗运动。本研究没有发现强有力的证据表明gpi连接的或天然的I-E-k在CHO细胞的质膜中有明显的限制。
Single-molecule epifluorescence microscopy was used to observe the translational motion of GPI-linked and native I-E-k class II MHC membrane proteins in the plasma membrane of CHO cells. The purpose of the study was to look for deviations from Brownian diffusion that might arise from barriers to this motion. Detergent extraction had suggested that these proteins may be confined to lipid microdomains; in the plasma membrane. The individual I-E-k proteins were visualized with a Cy5-labeled peptide that binds to a specific extracytoplasmic site common to both proteins. Single-molecule trajectories were used to compute a radial distribution of displacements, yielding average diffusion coefficients equal to 0.22 (GPI-linked I-E-k) and 0.18 mum(2)/s (native I-E-k). The relative diffusion of pairs of proteins was also studied for intermolecular separations in the range 0.3-1.0 mum, to distinguish between free diffusion of a protein molecule and diffusion of proteins restricted to a rapidly diffusing small domain. Both analyses show that motion is predominantly Brownian. This study finds no strong evidence for significant confinement of either GPI-linked or native I-E-k in the plasma membrane of CHO cells.