The inhibition of heme and globin synthesis by cobalt in rabbit reticulocytes and bone marrow

Abstract

Co 2+ was employed as an inhibitor of heme synthesis in rabbit reticulocytes and bone marrow cells. Heme synthesis was measured using [2- 14C]glycine and [4- 14C]δ-aminolevulinate. Globin synthesis was measured using [2- 14C]glycine, [ 14C]leucine and [ 14C]valine. Radioactive assays of partially purified globin revealed parallel rates of inhibition of heme and globin synthesis when the latter was labelled with [ 14C]leucine or [ 14C]valine. When [2- 14C]glycine was used as the radioactive precursor of globin, globin synthesis was apparently stimulated by Co 2+. However, when the amount of radioactivity in purified glycine labelled α-and β-globin chains was measured, it was found that globin synthesis was inhibited by Co 2+. It was concluded that Co 2+ does not dissociate heme and globin synthesis in erythroid cells when they are incubated in a medium optimal for hemoglobin synthesis, but rather inhibits both processes to the same extent. These results are relevant to the postulated regulatory role of heme in globin chain initiation.