CYP8B1
Description
The CYP8B1 (cytochrome P450 family 8 subfamily B member 1) is a protein-coding gene located on chromosome 3.
CYP8B1, also known as sterol 12-alpha-hydroxylase, is a human protein encoded by the CYP8B1 gene. It belongs to the cytochrome P450 superfamily, which are monooxygenases involved in drug metabolism, cholesterol synthesis, and steroid production. CYP8B1 is located in the endoplasmic reticulum membrane and converts 7 alpha-hydroxy-4-cholesten-3-one into 7-alpha,12-alpha-dihydroxy-4-cholesten-3-one. The relative levels of these two steroids determine the ratio of cholic acid and chenodeoxycholic acid, the primary bile acids secreted into bile. These bile acids affect the solubility of cholesterol and other lipids in the intestine, promoting their absorption. Notably, CYP8B1 is unique among cytochrome P450 genes as it lacks introns. Interestingly, the elephant, manatee, and naked mole rat lack functional copies of this gene and consequently do not produce cholic acid in their bile. This loss is likely due to relaxed selection pressures associated with dietary shifts towards lower lipid consumption.
CYP8B1 is a cytochrome P450 monooxygenase that plays a crucial role in the biosynthesis of primary bile acids. Specifically, it catalyzes the 12-alpha hydroxylation of 7-alpha-hydroxy-4-cholesten-3-one, a key intermediate in the pathway leading to cholic acid. This enzyme's activity directly influences the balance of cholic acid and chenodeoxycholic acid in bile, ultimately regulating the absorption of dietary lipids in the intestines. CYP8B1 utilizes molecular oxygen, inserting one oxygen atom into its substrate and reducing the second into water, with the required electrons provided by NADPH via cytochrome P450 reductase.
CYP8B1 is also known as CP8B, CYP12, CYPVIIIB1.
