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Control mechanisms in hemoglobin synthesis.

1966; National Institutes of Health; Volume: 26; Issue: 9 Linguagem: Inglês

Vernon M. Ingram, Robert M. Winslow,

Erythrocyte Function and Pathophysiology

Summary Human bone marrow was pulse labeled with radioactive amino acids for various times. Hemoglobin A after 3 min of pulse showed a sudden increase in the relative specific activities of peptides between position 90 and the COOH terminus in both the α and β chains. A control point in this region is postulated beyond which the growth of the polypeptide chains is markedly reduced, perhaps because of the assumption of a specific tertiary conformation of the growing chains after heme insertion. Pulse labeling of hemoglobin A 2 indicates that δ chains are assembled at a rate much less than that for either α and β chains of hemoglobin A or α chains of hemoglobin A 2 . This can, in part, account for the small quantity of hemoglobin A 2 with respect to hemoglobin A found in normal peripheral blood. Also, as cells age, their capacity to produce hemoglobin A 2 is lost at a greater rate than their capacity to produce hemoglobin A. The assembly of α chains for both hemoglobins A and A 2 proceeds at about the same rate, suggesting a common pool of α chains for the 2 hemoglobin types and their synthesis in the same cell.