CYP7B1

CYP7B1 (Cytochrome P450 Family 7 Subfamily B Member 1) is a Protein Coding gene. Diseases associated with CYP7B1 include Spastic Paraplegia 5A, Autosomal Recessive and Bile Acid Synthesis Defect, Congenital, 3. Among its related pathways are Metabolism and Cytochrome P450 - arranged by substrate type. Gene Ontology (GO) annotations related to this gene include iron ion binding and oxidoreductase activity, acting on paired donors, with incorporation or reduction of molecular oxygen. An important paralog of this gene is CYP7A1.

Full Name

Cytochrome P450 Family 7 Subfamily B Member 1

Function

A cytochrome P450 monooxygenase involved in the metabolism of endogenous oxysterols and steroid hormones, including neurosteroids (PubMed:10588945, PubMed:24491228).

Mechanistically, uses molecular oxygen inserting one oxygen atom into a substrate, and reducing the second into a water molecule, with two electrons provided by NADPH via cytochrome P450 reductase (CPR; NADPH-ferrihemoprotein reductase) (PubMed:10588945, PubMed:24491228).

Catalyzes the hydroxylation of carbon hydrogen bonds of steroids with a preference for 7-alpha position (PubMed:10588945, PubMed:24491228).

Usually metabolizes steroids carrying a hydroxy group at position 3, functioning as a 3-hydroxy steroid 7-alpha hydroxylase (PubMed:24491228).

Hydroxylates oxysterols, including 25-hydroxycholesterol and (25R)-cholest-5-ene-3beta,26-diol toward 7-alpha hydroxy derivatives, which may be transported to the liver and converted to bile acids (PubMed:9802883, PubMed:10588945).

Via its product 7-alpha,25-dihydroxycholesterol, a ligand for the chemotactic G protein-coupled receptor GPR183/EBI2, regulates B cell migration in germinal centers of lymphoid organs, thus guiding efficient maturation of plasma B cells and overall antigen-specific humoral immune response (By similarity).

7-alpha hydroxylates neurosteroids, including 3beta-hydroxyandrost-5-en-17-one (dehydroepiandrosterone) and pregnenolone, both involved in hippocampus-associated memory and learning (PubMed:24491228).

Metabolizes androstanoids toward 6- or 7-alpha hydroxy derivatives (PubMed:24491228).

Biological Process

B cell chemotaxis Source: UniProtKB
Bile acid biosynthetic process Source: GO_Central
Cholesterol homeostasis Source: GO_Central
Cholesterol metabolic process Source: UniProtKB-KW
Negative regulation of intracellular estrogen receptor signaling pathway Source: Ensembl
Positive regulation of epithelial cell proliferation Source: Ensembl
Prostate gland epithelium morphogenesis Source: Ensembl
Sterol metabolic process Source: Reactome

Cellular Location

Endoplasmic reticulum membrane; Microsome membrane

Involvement in disease

Spastic paraplegia 5A, autosomal recessive (SPG5A):
A form of spastic paraplegia, a neurodegenerative disorder characterized by a slow, gradual, progressive weakness and spasticity of the lower limbs. Rate of progression and the severity of symptoms are quite variable. Initial symptoms may include difficulty with balance, weakness and stiffness in the legs, muscle spasms, and dragging the toes when walking. In some forms of the disorder, bladder symptoms (such as incontinence) may appear, or the weakness and stiffness may spread to other parts of the body.
Congenital bile acid synthesis defect 3 (CBAS3):
A disorder resulting in severe cholestasis, cirrhosis and liver synthetic failure. Hepatic microsomal oxysterol 7-alpha-hydroxylase activity is undetectable.