Synthèse de l'hémoglobine par des systèmes acellulaires de réticulocytes

Abstract

The microsomes from rabbit reticulocytes incorporate [ 14C]valine in the presence or in the absence of pH-5 enzyme. The study of the rate of incorporation into microsomal protein and into hemoglobin suggests a metabolism of microsomal protein which is, in part, not related to hemoglobin formation. In the presence of pH-5 enzyme, microsomes and deoxycholate-insoluble ribosomes synthesized hemoglobin at equal rates. By addition of non-radioactive valine to microsomes labelled with [ 14C]valine, liberation of newly synthesized hemoglobin from the particles has been studied. The concentration of Mg 2+ has an influence on the synthesis of the microsomal precursor of hemoglobin, K + has an influence on the liberation of hemoglobin by microsomes. The incubation of microsomes prepared from rabbit reticulocytes with pH-5 enzyme prepared from human reticulocytes results in the synthesis of both types of hemoglobin which is in accord with results previously otained with cell-free systems of reticulocytes from other species. No synthesis of hemoglobin was detected upon incubation of reticulocyte microsomes with pH-5 enzyme from other organs or reticulocyte pH-5 enzyme with microsomes from other organs. These results are discussed in relation to our knowledge of the factors which carry the genetic information.