Involved in the post-translational conjugation of arginine to the N-terminal aspartate or glutamate of a protein. This arginylation is required for degradation of the protein via the ubiquitin pathway. Does not arginylate cysteine residues. an N-terminal L-alpha-aminoacyl-[protein] + L-arginyl-tRNA(Arg) = H(+) + N-terminal L-arginyl-L-amino acid-[protein] + tRNA(Arg) Monomer. Interacts with LIAT1. Widely expressed. Shows significantly higher activity than isoform ATE1-2. Belongs to the R-transferase family.