Granger B L, Lazarides E
Nature. 1985;313(5999):238-41. doi: 10.1038/313238a0.
The erythrocyte plasma membrane is lined with a network of extrinsic proteins, mainly spectrin and actin, which constitute a reticulum tethered to the intrinsic anion transport protein of the lipid bilayer through a linker protein, ankyrin. Protein 4.1 forms a stable ternary complex with spectrin and actin, thereby strengthening the reticulum and anchoring it directly to the lipid bilayer or to another intrinsic protein, glycophorin. It has been found recently that spectrin, ankyrin and protein 4.1 are not erythrocyte-specific; this has elucidated further the mechanisms of plasma membrane assembly and modelling during the differentiation of diverse tissues. We have shown previously that protein 4.1 in chickens is most abundant in erythrocytes and lens cells, but is scarce or absent from other spectrin-rich cell types. In addition, it exists as a family of related polypeptides showing differential expression in these two tissues, suggesting variant-specific functions. Here we show that the pattern of protein 4.1 variants changes during the terminal differentiation of erythroid and lenticular cells, with novel variants appearing in postmitotic cells. The accumulation of these variants may lead to the final stabilization of the plasma membrane skeletons of these cells.
红细胞质膜内衬有一层外在蛋白网络，主要是血影蛋白和肌动蛋白，它们构成一个网状结构，通过连接蛋白锚蛋白与脂质双层的内在阴离子转运蛋白相连。蛋白4.1与血影蛋白和肌动蛋白形成稳定的三元复合物，从而加强网状结构，并将其直接锚定在脂质双层或另一种内在蛋白血型糖蛋白上。最近发现，血影蛋白、锚蛋白和蛋白4.1并非红细胞所特有；这进一步阐明了不同组织分化过程中质膜组装和塑造的机制。我们之前已经表明，鸡体内的蛋白4.1在红细胞和晶状体细胞中含量最高，但在其他富含血影蛋白的细胞类型中则很少或不存在。此外，它以一组相关多肽的形式存在，在这两种组织中表现出差异表达，提示存在变体特异性功能。在此我们表明，蛋白4.1变体的模式在红细胞和晶状体细胞的终末分化过程中发生变化，有新的变体出现在有丝分裂后的细胞中。这些变体的积累可能导致这些细胞的质膜骨架最终稳定。
