ISOLATION OF A PEPTIDE THAT INHIBITS THE POSTTRANSLATIONAL ARGINYLATION OF PROTEINS IN RAT-BRAIN

All eukaryotic cells contain enzymes that are able to catalyze the tra nsfer of Arg from tRNA to the N-terminus of naturally short lived or d amaged cytosolic proteins. For certain test proteins, it has been show n that the addition of Arg to the N-terminus leads to their degradatio n via the ubiquitin proteolytic pathway. The mechanisms used by cells for identifying proteins for arginylation and regulating arginylation are not known. The present study reports the isolation of a peptide fr om rat brain that is able to inhibit the arginylation of proteins in b rain extracts. We suggest that this peptide is the physiological regul ator of arginylation in rat brain.