Description: Methylates (mono- and asymmetric dimethylation) the guanidino nitrogens of arginyl residues in some proteins, including histone H3, EP300/P300 and PABP1. May be involved in regulation of gene expression at different levels by using targets that regulate transcription, DNA packaging and mRNA stability and translation. During transcriptional activation by hormone- activated nuclear receptors (NR) enhances together with EP300/P300 the coactivator function of NCOA1/SRC1, NCOA2/GRIP1 and NCOA3/ACTR. Both the histone acetyltransferase activity of EP300/P300 and the histone methyltransferase activity of CARM1 are involved in chromatin remodeling. In androgen receptor-dependent activation acts as coactivator together with CTNNB1/beta-catenin and EP300/P300. Acts as coactivator in TCF7L2/TCF4 activation. Required for estrogen-dependent transcription. During myogenic transcriptional activation acts together with NCOA3/ACTR as coactivator for MEF2C and is involved in regulation of skeletal muscle differentiaton. In cAMP signaling pathways acts as corepressor by inhibiting CREB-dependent transcription. Methylation of arginine residues in the EP300/P300 KIX domain inhibits its interaction with the CREB KID domain and thus transcriptional activation. Together with EP300/P300 and HRMT1L2/PRMT1 seems to be involved in p53/TP53 transcriptional activation (By similarity).