Synthesis of Functional Proteins in X-irradiated Mammalian Cells

Abstract

RECOVERY from X-ray induced division delay in Chinese hamster cells cultured in vitro requires protein synthesis but not synthesis of DNA or RNA^1,2, suggesting that the primary lesion is at the level of translation. The question then arises whether or not normal proteins are synthesized during the recovery period. Although it is well established that the rate of amino-acid incorporation into polypeptide is only slightly reduced after moderate doses of X-irradiation^3–6, it does not necessarily follow that the protein species synthesized in these conditions are functional. For example, cessation of functional protein in the presence of low doses of puromycin is almost immediate despite the fact that the rate of amino-acid incorporation is only slightly affected⁷.