Ubiquitin is associated with aggregates of arginine modified proteins in injured nerves

Crush injury to rat sciatic nerves results in a 10-fold increase in the post-translational arginylation of proteins. In other systems, N-terminal arginylation leads to ubiquitination and proteolysis of the arginylated proteins. In the present experiments, proteins obtained from the 150 kg supernatant of crushed sciatic nerves were posttranslationally modified by 3H-arginine. These arginine modified proteins formed aggregates (precipitated at 20 kg) which then partially separated by SDS-PAGE were immunoreactive to a monoclonal antibody to ubiquitin. The results indicate that following injury to sciatic nerves, certain proteins are arginylated and ubiquitinated, probably targeting them for degradation. It is likely that these reactions help to rid cells of proteins damaged by the crush which would otherwise be cytotoxic.