Kodippili Gayani C, Giger Katie, Putt Karson S, Low Philip S
Department of Chemistry, Purdue University, West Lafayette, Indiana.
Institute for Drug Discovery, Purdue University, West Lafayette, Indiana.
Biophys J. 2020 Nov 3;119(9):1749-1759. doi: 10.1016/j.bpj.2020.09.012. Epub 2020 Sep 23.
Single-particle tracking offers a method to interrogate the organization of transmembrane proteins by measuring their mobilities within a cell's plasma membrane. Using this technique, the diffusion characteristics of the Duffy antigen (DARC), glycophorin A, band 3, and GLUT1 were compared under analogous conditions on intact human erythrocyte membranes. Microscopic diffusion coefficients revealed that the vast majority of all four transmembrane proteins exhibit very restricted movement but are not completely immobile. In fact, only 12% of GLUT1 resolved into a highly mobile subpopulation. Macroscopic diffusion coefficients and compartment sizes were also similar for all four proteins, with movements confined to the approximate dimensions of the "corrals" of the cortical spectrin cytoskeleton. Taken together, these data suggest that almost the entire populations of all four transmembrane proteins are immobilized by either the incorporation within large multiprotein complexes or entrapment within the protein network of the cortical spectrin cytoskeleton.
单粒子追踪提供了一种通过测量跨膜蛋白在细胞质膜内的迁移率来探究其组织方式的方法。利用该技术，在类似条件下比较了达菲抗原（DARC）、血型糖蛋白A、带3蛋白和葡萄糖转运蛋白1（GLUT1）在完整人红细胞膜上的扩散特性。微观扩散系数表明，所有这四种跨膜蛋白中的绝大多数表现出非常受限的移动，但并非完全静止不动。事实上，只有12%的GLUT1解析为一个高度可移动的亚群。所有这四种蛋白的宏观扩散系数和区室大小也相似，其移动局限于血影蛋白皮质细胞骨架“围栏”的大致尺寸范围内。综上所述，这些数据表明，所有这四种跨膜蛋白几乎全部通过纳入大型多蛋白复合物或被困在血影蛋白皮质细胞骨架的蛋白网络中而被固定。
