Anti-CARM1 antibodies are used in the immunodetection of the protein coactivator associated arginine methyltransferase 1. In humans, the canonical protein has a reported length of 608 amino acid residues and a mass of 65.9 kDa. Its subcellular localization is in the nucleus and cytoplasm. Alternative splicing is reported to yield 3 different isoforms for this protein. It is notably expressed in prostate adenocarcinomas and high-grade prostatic intraepithelial neoplasia. A member of the Protein arginine N-methyltransferase protein family, it is known to be involved with pathways of aging and chromatin organization. Post-translational modifications have been described, including methylation, ubiquitination and phosphorylation. Synonyms for this target antigen include histone-arginine methyltransferase CARM1, protein arginine N-methyltransferase 4, and PRMT4.