Ballas S K, Burka E R
J Lab Clin Med. 1978 Sep;92(3):387-92.
The role of the human erythrocyte membrane in degrading hemoglobin and hemoglobin subunits was investigated by determined the total radioactivity (cpm) of the nascent alpha and beta globin chains attached to the membrane after labeling of intact cells with 14C-leucine. In conditions characterized by balanced globin synthesis (normal and sickle cell anemia), the total radioactivity of membrane-attached alpha globin is always less than membrane-attached beta globin (alpha/beta = 0.60 +/- 0.10) despite the equal synthesis of alpha and beta chains in the hemolysate. In conditions characterized by unbalanced globin synthesis (alpha-thal and beta-thal traits) the cpm of membrane-attached alpha are also less than those of membrane-attached beta. Attachment of globin chains to the membrane is not related to the net ionic charge of individual chains, but the amount of attachment is related to the relative size of the free intracellular alpha chain pool. The alpha/beta ratio of less than 1 is not due to selective attachment of nascent beta chains or selective destruction of nascent alpha chains. The data indicate that part of the discrepancy between membrane and hemolysate alpha/beta radioactivities seen in the conditions studied is due to different rates of entry into the membrane and catabolism of newly labeled globin polypeptide chains by it.
通过用¹⁴C-亮氨酸标记完整细胞后，测定附着于膜上的新生α和β珠蛋白链的总放射性（每分钟计数，cpm），研究了人红细胞膜在降解血红蛋白和血红蛋白亚基中的作用。在以珠蛋白合成平衡为特征的条件下（正常和镰状细胞贫血），尽管溶血产物中α和β链的合成相等，但附着于膜上的α珠蛋白的总放射性总是低于附着于膜上的β珠蛋白（α/β = 0.60 ± 0.10）。在以珠蛋白合成不平衡为特征的条件下（α地中海贫血和β地中海贫血性状），附着于膜上的α珠蛋白的cpm也低于附着于膜上的β珠蛋白。珠蛋白链与膜的附着与单个链的净离子电荷无关，但附着量与游离细胞内α链池的相对大小有关。α/β比值小于1不是由于新生β链的选择性附着或新生α链的选择性破坏。数据表明，在所研究的条件下，膜与溶血产物中α/β放射性之间差异的部分原因是新标记的珠蛋白多肽链进入膜的速率以及被膜分解代谢的速率不同。
