An inhibitor(s) of globin mRNA translation in rabbit serum

1. A factor found in rabbit serum inhibits globin mRNA translation in vitro. 2. Inhibition of globin mRNA translation has been demonstrated in a cell-free rabbit reticulocyte lysate. 3. The inactivation of globin mRNA translation is not attributed to either serum albumin or ribonuclease activities. 4. Dialyzing the inhibitor for 24 hr at 4 degrees C does not result in the diminution of the inhibiting activity. However, the activity of the inhibitor is destroyed by heating to 70-80 degrees C for 5 min or by treatment with trypsin for 2 hr. 5. Ion exchange chromatography points to the inhibitor being a neutral protein, whereas, polyacrylamide gel electrophoresis reveals one major band with mol. wt 43 kDa. 6. The activity of the inhibiting material 3-fold greater in anemic serum than in normal serum. 7. These studies suggest that rabbit serum contains a protein inhibitor that may play a physiological role in regulating protein synthesis in red cells.