Abstract
Arginylation is a post-translational modification mediated by the arginyltransferase 1 (ATE1), which transfers the amino acid arginine to a protein or peptide substrate from a tRNA molecule. Initially, arginylation was thought to occur only on N-terminally exposed acidic residues, and its function was thought to be limited to targeting proteins for degradation. However, more recent data have shown that ATE1 can arginylate side chains of internal acidic residues in a protein without necessarily affecting metabolic stability. This greatly expands the potential targets and functions of arginylation, but tools for studying this process have remained limited. Here, we report the first global screen specifically for side-chain arginylation. We generate and validate "pan-arginylation" antibodies, which are designed to detect side-chain arginylation in any amino acid sequence context. We use these antibodies for immunoaffinity enrichment of side-chain arginylated proteins from wildtype and Ate1 knockout cell lysates. In this way, we identify a limited set of proteins that likely undergo ATE1-dependent side-chain arginylation and that are enriched in specific cellular roles, including translation, splicing, and the cytoskeleton.