Nuclear Receptor subfamily 1, group H, member 4 (NR1H4, also known as FXR) is a receptor for bile acids and has an important role in regulating energy metabolism in liver, muscle and adipose tissues in humans and animals. NR1H4 is highly expressed in liver and has a role in lipid metabolism, whereas none of the other protein-coding genes in the region has known biological links with cholesterol, further supporting a role for NR1H4 in regulation of cholesterol levels. NR1H4 have four isoforms, i.e., FXRalpha1, FXRalpha2, FXRbeta1, and FXRbeta2, and each isoform has a different expressional level and transcriptional activity depending on its location within specific tissues. (PMID: 14733360, PMID: 30787420)