Arginylation in a Partially Purified Fraction of 150 k xg Supernatants of Axoplasm and Injured Vertebrate Nerves.

Transfer RNA-mediated posttranslational protein modification by arginine has been demonstrated in vitro in axoplasm extruded from the giant axons of squid and in injured and regenerating vertebrate nerves. In nerve and axoplasm, the highest activity is found in a fraction of a 150,000 g supernatant containing high molecular weight protein/RNA complexes but lacking molecules of <5 kDa. Arginylation (and protein modification by other amino acids) is not found in more purified, reconstituted fractions. The data are interpreted as indicating that it is critical to recover the reaction components in high molecular weight protein/RNA complexes in order to maintain maximum physiological activity. The level of arginylation is greatest in injured and growing vertebrate nerves compared with intact nerves, suggesting a role for these reactions in nerve injury/repair and during axonal growth.