CYP7B1 : cytochrome P450 family 7 subfamily B member 1
Description
The CYP7B1 (cytochrome P450 family 7 subfamily B member 1) is a protein-coding gene located on chromosome 8.
The CYP7B1 gene is a member of the cytochrome P450 gene family, encoding an enzyme called oxysterol 7-alpha-hydroxylase. This enzyme is primarily produced in the liver and brain. In the liver, it breaks down cholesterol to form chenodeoxycholic acid, a component of bile for fat digestion. In the brain, it converts cholesterol to neurosteroids, increasing nerve cell activity and promoting cell survival and communication. The enzyme primarily converts the neurosteroid dehydroepiandrosterone (DHEA) into 7-hydroxy-DHEA. It helps maintain normal cholesterol levels in the brain and regulates the effects of neurosteroids through altering existing hormones within the pathway.
Cytochrome P450 7B1 (CYP7B1) is a monooxygenase involved in the metabolism of endogenous oxysterols and steroid hormones, including neurosteroids. It uses molecular oxygen, inserting one oxygen atom into a substrate and reducing the second into water. Two electrons are provided by NADPH via cytochrome P450 reductase (CPR). CYP7B1 catalyzes the hydroxylation of carbon-hydrogen bonds of steroids, preferring the 7-alpha position. It typically metabolizes steroids with a hydroxy group at position 3, functioning as a 3-hydroxy steroid 7-alpha hydroxylase. CYP7B1 hydroxylates oxysterols like 25-hydroxycholesterol and (25R)-cholest-5-ene-3beta,26-diol, converting them to 7-alpha hydroxy derivatives. These derivatives may be transported to the liver and converted to bile acids. Through its product 7-alpha,25-dihydroxycholesterol, a ligand for the chemotactic G protein-coupled receptor GPR183/EBI2, CYP7B1 regulates B cell migration in germinal centers, guiding efficient plasma B cell maturation and antigen-specific humoral immune response. CYP7B1 also 7-alpha hydroxylates neurosteroids like dehydroepiandrosterone (DHEA) and pregnenolone, involved in hippocampus-associated memory and learning. It metabolizes androstanoids to 6- or 7-alpha hydroxy derivatives.
CYP7B1 is also known as CBAS3, CP7B, SPG5A.
Associated Diseases
- Congenital bile acid synthesis defect type 3
- Spastic paraplegia 5A, autosomal recessive
- Autosomal recessive spastic paraplegia type 5A
- Bile acid synthesis defect, congenital, 3
- Spastic paraplegia type 5A
