Histone demethylase that specifically demethylates 'Lys-27' of histone H3, thereby playing a central role in histone code (PubMed:17713478, PubMed:17761849, PubMed:17851529). Demethylates trimethylated and dimethylated but not monomethylated H3 'Lys-27' (PubMed:17713478, PubMed:17761849, PubMed:17851529). Plays a central role in regulation of posterior development, by regulating HOX gene expression (PubMed:17851529).

Demethylation of 'Lys-27' of histone H3 is concomitant with methylation of 'Lys-4' of histone H3, and regulates the recruitment of the PRC1 complex and monoubiquitination of histone H2A (PubMed:17761849). Plays a demethylase-independent role in chromatin remodeling to regulate T-box family member-dependent gene expression (By similarity)

Interacts with TLE1 (By similarity). Component of the MLL2/3 complex (also named ASCOM complex), at least composed of KMT2D/MLL2 or KMT2C/MLL3, ASH2L, RBBP5, WDR5, NCOA6, DPY30, KDM6A (or KDM6B), PAXIP1/PTIP, PAGR1 and alpha- and beta-tubulin (PubMed:17500065, PubMed:17713478). Interacts with SUPT6H.

Interacts with SMARCA4 (By similarity). Interacts with PROSER1 (PubMed:34667079)

• Kabuki syndrome 2 (KABUK2)

  A congenital intellectual disability syndrome with additional features, including postnatal dwarfism, a peculiar facies characterized by long palpebral fissures with eversion of the lateral third of the lower eyelids, a broad and depressed nasal tip, large prominent earlobes, a cleft or high-arched palate, scoliosis, short fifth finger, persistence of fingerpads, radiographic abnormalities of the vertebrae, hands, and hip joints, and recurrent otitis media in infancy.