CYP8B1
Identifiers
Aliases	CYP8B1, CP8B, CYP12, cytochrome P450 family 8 subfamily B member 1
External IDs	OMIM: 602172 MGI: 1338044 HomoloGene: 3233 GeneCards: CYP8B1
Gene location (Human) Chr. Chromosome 3 (human)[1] Band 3p22.1 Start 42,856,005 bp[1] End 42,875,898 bp[1]
Gene location (Mouse) Chr. Chromosome 9 (mouse)[2] Band 9 72.73 cM|9 F4 Start 121,743,422 bp[2] End 121,745,371 bp[2]
RNA expression pattern Bgee Human Mouse (ortholog) Top expressed in right lobe of liver tibialis anterior muscle kidney sural nerve pancreatic ductal cell renal cortex renal medulla gallbladder right coronary artery left coronary artery Top expressed in left lobe of liver gallbladder sexually immature organism esophagus lip pancreas jejunum respiratory system lower respiratory tract lung More reference expression data BioGPS n/a
Gene ontology Molecular function monooxygenase activity iron ion binding oxygen binding oxidoreductase activity heme binding oxidoreductase activity, acting on paired donors, with incorporation or reduction of molecular oxygen metal ion binding 7alpha-hydroxycholest-4-en-3-one 12alpha-hydroxylase activity sterol 12-alpha-hydroxylase activity Cellular component integral component of membrane organelle membrane endoplasmic reticulum membrane endoplasmic reticulum membrane intracellular membrane-bounded organelle Biological process sterol metabolic process bile acid biosynthetic process Sources:Amigo / QuickGO
Orthologs Species Human Mouse Entrez 1582 13124 Ensembl ENSG00000180432 ENSMUSG00000050445 UniProt Q9UNU6 O88962 RefSeq (mRNA) NM_004391 NM_010012 RefSeq (protein) NP_004382 NP_034142 Location (UCSC) Chr 3: 42.86 – 42.88 Mb Chr 9: 121.74 – 121.75 Mb PubMed search [3] [4]
Wikidata
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CYP8B1 (cytochrome P450, family 8, subfamily B, polypeptide 1) also known as sterol 12-alpha-hydroxylase is a protein which in humans is encoded by the CYP8B1 gene.^[5]

This gene encodes a member of the cytochrome P450 superfamily of enzymes. The cytochrome P450 proteins are monooxygenases which catalyze many reactions involved in drug metabolism and synthesis of cholesterol, steroids and other lipids.

CYP8B1 is an endoplasmic reticulum membrane protein and catalyzes the conversion of 7 alpha-hydroxy-4-cholesten-3-one into 7-alpha,12-alpha-dihydroxy-4-cholesten-3-one. The balance between these two steroids determines the relative amounts of the two primary bile acids, cholic acid and chenodeoxycholic acid, both of which are secreted in the bile. In the intestine these bile acids affect the solubility of cholesterol and other lipids, promoting their absorption.

CYP8B1 is unique among the cytochrome P450 genes in that it is intronless.^[6]

The elephant, manatee and naked mole rat have inactive copies of this gene and lack cholic acid in their bile.^[7] Relaxed selection resulting from changes in diet to consume less lipids might have contributed to the loss of this gene in several species.^[8]