Fukuda M N, Klier G, Yu J, Scartezzini P
Blood. 1986 Aug;68(2):521-9.
Congenital dyserythropoietic anemia type II (CDA II or HEMPAS) is a genetic anemia caused by membrane abnormality. Our previous studies indicated that in HEMPAS, erythrocytes band 3 and band 4.5 are not glycosylated by polylactosaminoglycans. The present study was aimed at determining how such underglycosylated band 3 behaves in erythrocyte membranes. By using anti-band 3 antibodies, immunogold electron microscopy revealed that band 3s are clustered in HEMPAS erythrocyte membranes. By freeze-fracture electron microscopy, band 3s were also seen as lightly clumped intramembrane particles on a protoplasmic fracture face. Erythrocyte precursor cells stained by anti-band 3 antibodies showed that band 3s are present in the cytoplasmic area of the reticulocytes as scattered single particles. However, in young erythrocytes in which intracellular membranes are almost degenerated, band 3s were clustered in the cytoplasmic area of the cell. These observations suggest that band 3s cluster before they are incorporated into the plasma membranes of HEMPAS erythrocytes. In contrast to band 3, glycophorin A detected by anti-glycophorin A antibodies did not show a noticeable difference between normal and HEMPAS. Such a clustering of band 3 may cause abnormal localization of band 3-associated proteins and may thus result in the macroscopic membrane abnormality seen in HEMPAS erythrocytes.
II型先天性红细胞生成异常性贫血（CDA II或HEMPAS）是一种由膜异常引起的遗传性贫血。我们之前的研究表明，在HEMPAS中，红细胞带3和带4.5未被聚乳糖胺聚糖糖基化。本研究旨在确定这种低糖基化的带3在红细胞膜中的行为方式。通过使用抗带3抗体，免疫金电子显微镜显示带3在HEMPAS红细胞膜中聚集。通过冷冻断裂电子显微镜观察，在原生质断裂面上，带3也表现为轻度聚集的膜内颗粒。用抗带3抗体染色的红细胞前体细胞显示，带3以分散的单个颗粒形式存在于网织红细胞的细胞质区域。然而，在细胞内膜几乎退化的年轻红细胞中，带3聚集在细胞的细胞质区域。这些观察结果表明，带3在被整合到HEMPAS红细胞的质膜之前就发生了聚集。与带3不同，用抗血型糖蛋白A抗体检测到的血型糖蛋白A在正常细胞和HEMPAS细胞之间没有明显差异。带3的这种聚集可能会导致带3相关蛋白的异常定位，从而可能导致HEMPAS红细胞中出现宏观的膜异常。
