The function of Ensembl gene identifier ENSG00000180432 (CYP8B1, cytochrome P450 family 8 subfamily B member 1) is as follows. Sterol 12-alpha-hydroxylase involved in primary bile acid biosynthesis by catalyzing the 12alpha-hydroxylation of key intermediates including 7alpha-hydroxycholest-4-en-3-one, 3alpha,7alpha-dihydroxy-5beta-cholestan-26-oate and chenodeoxycholate along the classic pathway (PubMed:10051404, PubMed:30465713, PubMed:39214664). May also hydroxylate 5beta-cholestane-3alpha,7alpha- diol (By similarity). Functions as a monooxygenase, inserting one atom of molecular oxygen into substrates while reducing the second to water, using electrons supplied by NADPH via cytochrome P450 reductase (CPR) (By similarity). Controls biliary balance of cholic acid and chenodeoxycholic acid, thereby regulating intestinal absorption of dietary lipids (By similarity). {ECO:0000250|UniProtKB:O02766, ECO:0000250|UniProtKB:O88962, ECO:0000269|PubMed:10051404, ECO:0000269|PubMed:30465713, ECO:0000269|PubMed:39214664}.