Nuclear receptor that acts as a key metabolic sensor by regulating the expression of genes involved in bile acid synthesis, cholesterol homeostasis and triglyceride synthesis. Together with the oxysterol receptors NR1H3/LXR-alpha and NR1H2/LXR-beta, acts as an essential transcriptional regulator of lipid metabolism. Plays an anti-inflammatory role during the hepatic acute phase response by acting as a corepressor: inhibits the hepatic acute phase response by preventing dissociation of the N-Cor corepressor complex (PubMed:20159957). Binds to the sequence element 5'-AACGACCGACCTTGAG-3' of the enhancer II of hepatitis B virus genes, a critical cis-element of their expression and regulation. May be responsible for the liver-specific activity of enhancer II, probably in combination with other hepatocyte transcription factors. Key regulator of cholesterol 7-alpha-hydroxylase gene (CYP7A) expression in liver. May also contribute to the regulation of pancreas-specific genes and play important roles in embryonic development. Activates the transcription of CYP2C38 (By similarity). Binds DNA as a monomer (By similarity). Interacts with GRIP1, NCOA2 and NR0B2 (PubMed:15707893, PubMed:15723037, PubMed:15897460, PubMed:16289203). Interacts (when sumoylated) with GPS2; interaction with GPS2 onto hepatic acute phase protein promoters prevents N-Cor corepressor complex dissociation (PubMed:20159957). Abundantly expressed in pancreas, less in liver, very low levels in heart and lung. Expressed in the Hep-G2 cell line. Isoform 1 and isoform 2 seem to be present in fetal and adult liver and Hep-G2 cells. Sumoylated by SUMO1 at Lys-270 during the hepatic acute phase response, leading to promote interaction with GPS2 and prevent N-Cor corepressor complex dissociation. Does not induce CYP7A promoter activity. Belongs to the nuclear hormone receptor family. NR5 subfamily.