EVIDENCE FOR AN INHIBITOR IN CONTROL OF GLOBIN SYNTHESIS BY HEMIN IN A RETICULOCYTE LYSATE

The synthesis of hemoglobin by a reticulocyte lysate is stimulated several fold by the addition of hemin. The ability to respond to hemin is completely lost if the lysate is held for a short time at 34°C, but only slightly reduced if held at 0°C. Hemoglobin synthesis by reconstituted lysates prepared by combinations of ribosomal and supernatant fractions from hemin-responsive and -unresponsive lysates indicated that the factor mediating hemin stimulation is in the supernatant fluid. Addition of supernatant fraction from an unresponsive lysate to an incorporating system containing a responsive lysate markedly decreased the stimulation of globin synthesis by hemin. These results suggest that hemin promotes globin synthesis by preventing the formation of an inhibitor of chain initiation in the cell sap. © 1969.