AMINO ACID INCORPORATION BY FRACTIONS OF LIVER CELLS FROM NORMAL AND ADRENALECTOMIZED RATS.
ARMY MEDICAL RESEARCH LAB FORT KNOX KY
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The incorporation of leucine-14C into protein, using cell-free preparations from liver of normal and adrenalectomized rats was studied. Nuclei, mitochondria, microsomes, post-microsomal fractions and ribonucleoprotein RNP particles from the same groups of animals were tested for their incorporating activity under the same experimental conditions. The microsomes and RNP-particles were further fractionated by triton X-100 or sonoration treatment and the subfractions obtained were also tested for their amino acid incorporating activity. Of all the cellular fractions the RNP-particles manifested the greatest ability to incorporate the amino acid into protein. Further fractionation of these particles did not enhance the incorporating activity. The microsomes, which showed an incorporating activity lower than that of the post-microsomal fraction and much lower than that of the RNP-particles, when subjected to further fractionation liberated subfractions with greatly enhanced activity with some subfractions this activity was similar to that displayed by the corresponding RNP-particles. Ribonuclease inhibited considerably the incorporating activity of microsomal and post-microsomal fractions, but the inhibition was much smaller on the incorporating activity of the RNP-particles. Author