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PHD domain 2 found in Histone-lysine N-methyltransferase 2B (KMT2B) KMT2B, also termed trithorax homolog 2 or WW domain-binding protein 7 (WBP-7), is encoded by the gene that was first named myeloid/lymphoid or mixed-lineage leukemia 2 (MLL2), a second human homolog of Drosophila trithorax, located on chromosome 19. It belongs to the MLL subfamily of H3K4-specific histone lysine methyltransferases (KMT2) and is vital for normal mammalian embryonic development. KMT2B functions as the catalytic subunit in the MLL2 complex, which contains WDR5, RbBP5, ASH2L and DPY30 as integral core subunits required for the efficient methylation activity of the complex. The MLL2 complex is highly active and specific for histone 3lysine 4 (H3K4) methylation, which stimulates chromatin transcription in a SAM- and H3K4-dependent manner. Moreover, KMT2B 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. KMT2B contains a CxxC (x for any residue) zinc finger domain, three plant homeodomain (PHD), 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 second PHD finger.
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