7-alpha-hydroxycholest-4-en-3-one 12-alpha-hydroxylase is a protein in humans that is encoded by CYP8B1 gene. Involved in bile acid synthesis and is responsible for the conversion of 7 alpha-hydroxy-4-cholesten-3-one into 7 alpha, 12 alpha-dihydroxy-4-cholesten-3-one. Responsible for the balance between formation of cholic acid and chenodeoxycholic acid. Has a rather broad substrate specificity including a number of 7-alpha-hydroxylated C27 steroids.