Paradoxical stimulation by amino acids of the degradation of [ 35S]methionine-labelled, short-lived protein in isolated rat hepatocytes

Abstract

A complete amino acid mixture inhibited the degradation of long-lived and [ 14C]valine-labelled short-lived protein in isolated rat hepatocytes, but paradoxically stimulated the degradation of [ 35S]methionine-labelled short-lived protein. The stimulation persisted in the presence of autophagic-lysosomal pathway inhibitors like 3-methyladenine and propylamine, indicating the existence of an hitherto unrecognized non-lysosomal degradation mechanism with selectivity towards methionine-rich proteins or peptide regions.