Further Studies on the Stimulation of Adrenal Protein Synthesis by ACTH: An Effect on Microsomes and Ribosomes

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Abstract
The effects of ACTH administration on in vitro incorporation of 14C-glycine into protein in cell-free systems of the rat adrenal have been studied. When incubated with 105,000 ×g supernatant (from control or ACTH-stimulated adrenals) in an amino acid incorporating system, the microsomes from ACTH-stimulated adrenals were more active for 14C-glycine incorporation than equivalent amounts of control microsomes. This effect was also demonstrable in ribosomes isolated by desoxycholate extraction of microsomes, indicating that the effect of ACTH on adrenal microsomes is due to changes in the ribosomal fraction. Ribosomes from ACTH-stimulated adrenals were more active than control ribosomes when compared either on a gramequivalent basis or in terms of ribosomal- RNA. These results indicate that ACTH administration enhances the capacity of adrenal microsomes for incorporation of 14C-glycine into protein by induction of an increased amount and activity of ribosomal-RNA. (Endocrinology74: 579, 1964)