Member‐associated changes during erythropoiesis. On the mechanism of maturation of reticulocytes to erythrocytes

作者：Stephen E. Zweig, K. T. Tokuyasu, Sherwin J. Singer · 发表于：Journal of Supramolecular Structure and Cellular Biochemistry · 年份：1981 · DOI：10.1002/jsscb.380170207 · 被引用次数：32 · 研究领域：Erythrocyte Function and Pathophysiology、Blood properties and coagulation、Pancreatic function and diabetes

The mature mammalian erythrocyte has a unique membranoskeleton, the spectrin-actin complex, which is responsible for many of the unusual membrane properties of the erythrocyte. Previous studies have shown that in successive stages of differentiation of the erythropoietic series leading to the mature erythrocyte there is a progressive increase in the density of spectrin associated with the membranes of these cells. An important stage of this progression occurs during the enucleation of the late erythroblast to produce the incipient reticulocyte, when all of the spectrin of the former cell is sequestered to the membrane of the reticulocyte. The reticulocyte itself, however, does not exhibit a fully formed membranoskeleton. In particular, the in vitro binding of multivalent ligands to specific membrane receptors on the reticulocyte was shown to cause a clustering of some fractions of these ligand-receptor complexes into special mobile domains on the cell surface. These domains of clustered ligand-receptor complexes became invaginated and endocytosed as small vesicles. By immunoelectron microscopic experiments, these invaginations and endocytosed vesicles were found to be specifically free of spectrin on their cytoplasmic surfaces. These earlier findings then raised the possibility that the maturation of reticulocytes to mature erythrocytes in vivo might involve a progressive loss of reticulocyte membrane free of spectrin, thereby producing a still more concentrated spectrin-acti...