The mammalian PRMT family currently contains nine highly related members; all harbor signature motifs I, post-I, II, and III, and the conserved THW loop (in black bars). FBXO11 might have arginine methyltransferase activity, but is not structurally related to the other PRMTs and required “forced” alignments to identify putative signature motifs (in gray bars). Protein domains that might assist in substrate recognition are marked in gray boxes. The accession numbers for the PRMTs are as follows: hPRMT1 (AAF62893), hPRMT2 (AAH00727), hPRMT3 (AAC39837), hCARM1 (NP_954592), hPRMT5 (AAF04502), hPRMT6 (Q96LA8), hPRMT7 (NP_061896), mPRMT8 (DAA01382), hPRMT9 (AAH64403) and mFBXO11 (AAI28480).