Willingham M C, Strader C D, Lefkowitz R J, Pastan I
Exp Cell Res. 1984 Apr;151(2):573-7. doi: 10.1016/0014-4827(84)90406-3.
We have examined nucleated erythrocytes of frog and turkey for the presence of clathrin-coated structures using electron microscopy and immunocytochemistry. By electron microscopy, coated pits were found on the plasma membrane of peripheral blood erythrocytes of both species. These structures had an appearance similar to coated pits seen in non-erythroid mammalian cells. Using immunofluorescence with anti-(bovine) clathrin antibody, erythrocytes of both species showed punctate membrane fluorescence similar to the pattern of coated pits seen in other cells. By both methods, frog erythrocytes showed considerable heterogeneity, such that only about 50% of the cells showed significant numbers of coated pits, usually fewer than 20-50 per cell. In contrast, the vast majority of turkey erythrocytes showed no detectable coated pits, but occasional cells (less than 10%) showed large numbers of coated structures. These results suggest that a functional endocytic system may be present in a subpopulation of these nucleated erythrocytes. These findings may be of significance in understanding the ligand-induced loss of some receptors from the surface of these cells, and may serve as an indication of morphologic differentiation.
我们使用电子显微镜和免疫细胞化学方法检查了青蛙和火鸡的有核红细胞中是否存在网格蛋白包被结构。通过电子显微镜观察，在这两个物种的外周血红细胞质膜上发现了包被小窝。这些结构的外观与在非红细胞系哺乳动物细胞中看到的包被小窝相似。使用抗（牛）网格蛋白抗体进行免疫荧光检测，这两个物种的红细胞均显示出点状膜荧光，类似于在其他细胞中看到的包被小窝模式。通过这两种方法，青蛙红细胞表现出相当大的异质性，以至于只有约50%的细胞显示出大量的包被小窝，每个细胞通常少于20 - 50个。相比之下，绝大多数火鸡红细胞未检测到包被小窝，但偶尔有细胞（少于10%）显示出大量的包被结构。这些结果表明，在这些有核红细胞的一个亚群中可能存在功能性内吞系统。这些发现对于理解配体诱导这些细胞表面某些受体的丢失可能具有重要意义，并且可能作为形态学分化的一个指标。
