Transcription coactivator that binds to the 5'-AATA[CT]-3' core sequence and plays a key role in adipogenesis and liver development. Acts by forming a complex with phosphorylated PHF2, which mediates demethylation at Lys-337, leading to target the PHF2-ARID5B complex to target promoters, where PHF2 mediates demethylation of dimethylated 'Lys-9' of histone H3 (H3K9me2), followed by transcription activation of target genes. The PHF2-ARID5B complex acts as a coactivator of HNF4A in liver (By similarity). Required for adipogenesis: regulates triglyceride metabolism in adipocytes by regulating expression of adipogenic genes. Overexpression leads to induction of smooth muscle marker genes, suggesting that it may also act as a regulator of smooth muscle cell differentiation and proliferation. Widely expressed. Expressed in lung, heart, small intestine, kidney, muscle and brain. Also expressed in spleen, thymus, endocrine organs and in uterus and testis. First detected in the intermediate plate mesoderm, and subsequently in the nephrogenic cords of the urogenital ridges. Expressed in the developing limb. Also expressed in the myotome of the somites from 9.5 dpc, the oro-nasopharyngeal ectoderm and underlying mesenchyme, otic vesicles, the gut and its derivatives, and transiently in the liver at 11.5 dpc. During smooth muscle cell differentiation in vitro. Upon adipogenesis. The ARID domain mediates the interaction with DNA. Methylation at Lys-337 prevents DNA-binding. Demethylation by PHF2 promotes recruitment of the PHF2-ARID5B complex to promoters (By similarity). High rate of neonatal mortality. Embryonic growth or birth weight are not effected, while lipid accumulation is severely reduced in brown adipose neonates at 24 hours of age. Mice weigh significantly less than controls from postnatal day 5 onward. Adult mice are lean, with significant reductions in brown and white adipose tissues, and in the percentage of body fat. Mice are also resistant to weight gains and obesity when maintained on high-fat diets. Belongs to the ARID5B family. Truncated C-terminus. Truncated N-terminus.