Transcriptional regulator which controls the expression of hepatic genes during the transition of endodermal cells to hepatic progenitor cells, facilitating the recruitment of RNA pol II to the promoters of target genes (By similarity). Activates the transcription of CYP2C38 (By similarity). Represses the CLOCK-ARNTL/BMAL1 transcriptional activity and is essential for circadian rhythm maintenance and period regulation in the liver and colon cells (By similarity). Homodimerization is required for HNF4-alpha to bind to its recognition site (PubMed:12193589). Interacts with CLOCK, ARNTL, CRY1, CRY2, PER1 and PER2 (By similarity). Interacts with NR0B2/SHP; the resulting heterodimer is transcriptionnally inactive (By similarity). Interacts with DDX3X; this interaction disrupts the interaction between HNF4 and NR0B2 that forms inactive heterodimers and enhances the formation of active HNF4 homodimers (By similarity). Liver, kidney and intestine. The 9aaTAD motif is a transactivation domain present in a large number of yeast and animal transcription factors. Phosphorylation at Ser-313 by AMPK reduces the ability to form homodimers and bind DNA (By similarity). Phosphorylated in the recognition sequence R-R-S-S near the DNA-binding domain; phosphorylation results in decrease in DNA-binding activity. Phosphorylation of HNF4 depends on the diet and is decreased by a carbohydrate-rich diet and is increased by fasting. The N-terminus is blocked. Acetylation at Lys-458 lowers transcriptional activation by about two-fold. DNA-binding activity of phosphorylated protein is reduced by fasting and by inducers of intracellular cyclic AMP. Binds fatty acids. Belongs to the nuclear hormone receptor family. NR2 subfamily. Truncated N-terminus. Truncated N-terminus.