Evidence supporting a physiological role for the hemin-controlled translational repressor of globin synthesis in reticulocytes.

The synthesis of heme and globin in rabbit reticulocytes was compared at 35 and 25 degrees C. The lower temperature decreased heme synthesis significantly more than globin synthesis and resulted in a much greater accumulation of globin dimers. After 16 h of incubation in the absence of iron, globin synthesis in reticulocytes which were at 35 degrees C could not be stimulated by iron, whereas cells which were at 25 degrees C responded with nearly control levels of globin synthesis. Since the formation of the hemin-controlled translational repressor in reticulocyte lysates is also decreased much more than protein synthesis at reduced temperature the results provide evidence for a physiological role for the translational repressor in controlling globin synthesis in reticulocytes.