Domain structure of the plasma membrane : interaction between membrane skeleton and membrane receptors

用40 nm胶体金包被转铁蛋白受体，用纳米级特殊精度和视频速率时间分辨率的视频增强对比光学显微镜研究了转铁蛋白受体分子在培养的正常大鼠肾成纤维细胞质膜中的运动。在-0.25微米^2的区域内，大部分的运动轨迹是受限扩散型的。区域内的运动是随机的，扩散系数为-10^~(-9)cm^2/S，这与蛋白质在质膜中的自由布朗扩散的预期一致。受体分子以0.034s^~(-1)~(-1)~(-1)的平均频率从一个结构域移动到相邻的一个结构域，这表明质膜是为膜受体的扩散而划分的，长距离扩散是连续间隔跳跃的结果。细胞骨架的部分破坏表明，隔室之间的边界是由动态波动的膜骨架组成的。

Movements of transferrin receptor molecules in the plasma membrane of cultured normal rat kidney fibroblastic cells were investigated by video-enhanced contrast optical microscopy with nanometer-level special precision and video-rate temporal resolution by lebeling the receptor with the ligand-coated 40-nm colloidal gold particles. Most of the movement trajectories are of the confined diffusion type within domains of -0.25mum^2. Movement within the domains is random with a diffusion coefficient -10^<-9> cm^2/s, which is consistent with that expected for free Brownian diffusion of proteins in the plasma membrane. The receptor molecules move from one domain to one of the adjacent domains at an average frequency of 0.034s^<-1>, indicating that the plasma membrane is compartmentalized for diffusion of membrane receptors and that long-range diffusion is the result of successive intercompartmental jumps. Partial destruction of the cytoskeleton suggest that the boundaries between compartments are made of dynamically fluctuating membrane skeletons.