Involved in the post-translational conjugation of arginine to the N-terminal aspartate or glutamate of a protein (PubMed:34893540). This arginylation is required for degradation of the protein via the ubiquitin pathway (PubMed:34893540). Does not arginylate cysteine residues (By similarity). {ECO:0000250|UniProtKB:Q9Z2A5, ECO:0000269|PubMed:34893540}. This is the function of Ensembl gene identifier ENSG00000107669 (ATE1, arginyltransferase 1).