Protein arginine N-methyltransferases, such as CARM1, catalyze the transfer of a methyl group from S-adenosyl-L-methionine to the side chain nitrogens of arginine residues within proteins to form methylated arginine derivatives and S-adenosyl-L-homocysteine. Protein arginine methylation has been implicated in signal transduction, metabolism of nascent pre-RNA, and transcriptional activation (Frankel et al. 2002 (PubMed 11724789). Tissue specificity: Overexpressed in prostate adenocarcinomas and high-grade prostatic intraepithelial neoplasia. Synonyms: PRMT4, CARM1