PHD finger 3 found in histone-lysine N-methyltransferase 2A (KMT2A) and 2B (KMT2B)
This family includes histone-lysine N-methyltransferase trithorax (Trx) like proteins, KMT2A (MLL1) and KMT2B (MLL2), which comprise the mammalian Trx branch of the COMPASS family, and are both essential for mammalian embryonic development. KMT2A regulates chromatin-mediated transcription through the catalysis of methylation of histone 3 lysine 4 (H3K4), and is frequently rearranged in acute leukemia. KMT2A functions as the catalytic subunit in the MLL1 complex. KMT2B is a second human homolog of Drosophila trithorax, located on chromosome 19 and functions as the catalytic subunit in the MLL2 complex. It plays a critical role in memory formation through mediating hippocampal H3K4 di- and trimethylation. It is also required for RNA polymerase II association and protection from DNA methylation at the MagohB CpG island promoter. Both KMT2A and KMT2B contain a CxxC (x for any residue) zinc finger domain, three plant homeodomain (PHD) fingers, an extended PHD (ePHD) finger, Cys2HisCys5HisCys2His, two FY (phenylalanine tyrosine)-rich domains, and a SET (Suppressor of variegation, Enhancer of zeste, Trithorax) domain. This model corresponds to the third PHD finger.
Jiyao W et al.(2023). "The conserved domain database in 2023.",