N-TERMINAL ARGINYLATION OF SCIATIC-NERVE AND BRAIN PROTEINS FOLLOWINGINJURY

N-terminal protein arginylation has been demonstrated in vitro and in situ and has been reported to increase following injury to sciatic ner ves of rats. The present study attempts to demonstrate these reactions in vivo by applying [H-3]Arg to the cut end of sciatic nerves in anes thetized rats and assaying for N-terminal arginylation using Ed-nan ch emistry and acid precipitation of labeled proteins in the proximal ner ve segment. No evidence was found for arginylation in an aqueous solub le fraction. However, N-terminal arginylation was detected in a urea s oluble fraction at 2 hours after nerve crush. The data show that argin ylation of rat sciatic nerve proteins occurs in vivo and suggest that the arginylated proteins formed an aqueous insoluble/urea soluble aggr egate after arginylation. In other experiments, rat brains were injure d and assayed for arginylation in vitro to test the hypothesis that in jury causes an up-regulation of these reactions. Results showed an act ivation of the reaction at 2 hours post crush and indicate that increa ses in N-terminal arginylation are likely to be a general response to injury in nervous tissue.