Rapidly turning over RNA as a limiting factor in protein synthesis: effect of actinomycin D

Abstract

It has been suggested that the inhibitory effect of actinomycin D on protein synthesis in vivo may be due to loss of a labile RNA fraction, presumably messenger RNA, following the inhibition of DNA-dependent RNA synthesis. Considerable deviation from a simple proportionality between the amount of labile RNA and the rate of protein synthesis in the presence of actinomycin D has been observed. The bulk of experimental data support the view that whereas RNA is synthesized in nucleus, a major fraction of protein synthesis is carried out in cytoplasm. The rate of transfer of messenger RNA from nucleus to cytoplasm may have profound influence on the kinetics of protein synthesis. In the present paper kinetic implications of a multi-compartment model for messenger RNA are examined. The analysis suggests that the observed inhibitory effect of actinomycin on protein synthesis is not inconsistent with the possible role of labile RNA as a template.