INHBB

INHBB is a gene that encodes the inhibin beta B subunit in humans. This protein is a subunit of both activin and inhibin, two closely related glycoproteins with opposing biological effects.

Function

The INHBB gene is a member of the transforming growth factor beta (TGF-beta) superfamily. The encoded protein is synthesized as a large precursor molecule that is cleaved to form a 12 kDa mature protein subunit and a 26 kDa N-terminal propeptide. This protein subunit can form homodimers or can be paired with the beta A subunit to form a heterodimer, both of which are active in inhibin and activin complexes.

The bioactive complex of inhibin B (alpha and beta B subunit) acts as a negative feedback regulator of follicle-stimulating hormone (FSH) secretion. On the other hand, the activin complex (beta B homodimer) stimulates FSH secretion. Therefore, the balance of inhibin B and activin secretion regulates FSH secretion and, consequently, reproductive function.

Clinical significance

Mutations in the INHBB gene are associated with premature ovarian failure and polycystic ovary syndrome. In addition, elevated levels of inhibin B are found in individuals with granulosa cell tumors and are used as a tumor marker in clinical tests.

See also

• Inhibin
• Activin
• Follicle-stimulating hormone
• Transforming growth factor beta