Control of macromolecular synthesis in proliferating and resting Syrian hamster cells in monolayer culture. I. Ribosome function.

Abstract

AbstractThe rate of protein synthesis per cell in cultured hamster embryo fibroblasts in the stationary growth phase falls to about one third of the rate in the exponential growth phase. This reduction can be entirely accounted for by the following observations: (1) the average cell in stationary phase contains about one‐half the number of ribosomes per cell compared to the average cell in exponential phase; (2) only two thirds of the ribosomes are bound to polysomes in stationary phase, while nearly all of the ribosomes are polysome‐bound in exponential phase.In stationary phase, ribosomes which are polysome‐bound function with the same efficiency and produce proteins of approximately the same average length as in exponential phase. Experimental findings are presented which suggest that the generation of a higher proportion of free ribosomes in stationary phase in not due to a limitation in messenger RNA, but to a decreased attachment probability of ribosomes to messenger RNA.