Distribution of free and membrane-bound ribosomes after corticosterone administration in perfused rat liver.

Contrasting results have been reported on the effect of steroid hormones on the interaction between ribosomes and endoplasmic reticulum in rat liver. Exposure to high gravitational forces for a long time was found necessary to obtain a constant ratio of free to membrane-bound ribosomes from the post-nuclear supernatant. Using these isolation conditions, rat liver from fasted controls and from fasted, adrenalectomized rats contain both about 45% membranebound ribosomes. Addition of corticosterone to the livers from adrenalectomized rats did not increase the pool of bound ribosomes more than in the control livers; 55% was found in both. Corticosterone had therefore no effect on the pool sizes of free and membrane-bound ribosomes in perfused rat livers.