The effect of iron administration on the incorporation of [14C] leucine into ferritin by rat-liver systems.

Abstract

Abstract The incorporation of [ 14 ]leucine into rat-liver ferritin by a microsomal system, supplemented with ATP, GTP, and a system to generate the nucleoside triphosphates, was investigated. Administration of iron to the rats increased the incorporating activity of the cell-free system. The effect was fairly specific for ferritin since the incorporation of amino acids into rat serum was not affected by the iron injection. After incubation, the proteins were purified by various methods prior to the final immunoelectrophoresis. Radioactivity of ferritin and serum albumin was estimated by autoradiography of the immunoelectrophoretic plates or by counting the antigen-antibody precipitates of the proteins. No significant amount of labelled proteins of moderate size but with antigen determinants similar to those of apoferritin could be demonstrated by means of molecular sieving on Sephadex G-200. When rats were injected with actinomycin D, one hour prior to the iron injection, the stimulatory effect of iron of the labelling of ferritin was maintained.