Relationship Between Protein Synthesis and Secretion in Liver Cells and the State of the Adenine Nucleotide System

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Abstract
Adenine nucleotide levels could be precisely and reproducibly adjusted in rat liver cell suspensions by partially depleting the ATP pool with D-fructose or glycerol. Rates of protein synthesis and secretion were correlated with intracellular levels of ATP and with derived parameters, such as the adenylate energy charge. Half the maximum rate of incorporation of leucine into protein was observed at an energy charge of 0.80, a ratio of ATP to ADP of 2.6, and an ATP level of 1.05 .mu.mol/g of wet cells. Proteins were secreted with half the maximum rate at an energy charge of 0.85, a ratio of ATP to ADP of 3.1 and an ATP concentration of 1.1 .mu.mol/g of wet cells. Protein secretion did not depend on continued synthesis. Inhibitors of oxidative phosphorylation inhibited protein secretion in addition to protein synthesis.