Activin-B Active (INHBB) Human Active Protein

The inhibin beta B subunit joins the alpha subunit to form a pituitary FSH secretion inhibitor. Inhibin has been shown to regulate gonadal stromal cell proliferation negatively and to have tumour-suppressor activity. In addition, serum levels of inhibin have been shown to reflect the size of granulosa-cell tumors and can therefore be used as a marker for primary as well as recurrent disease. Because expression in gonadal and various extragonadal tissues may vary severalfold in a tissue-specific fashion, it is proposed that inhibin may be both a growth/differentiation factor and a hormone. Furthermore, the beta B subunit forms a homodimer, activin B, and also joins with the beta A subunit to form a heterodimer, activin AB, both of which stimulate FSH secretion. [provided by RefSeq, Jul 2008]

INHBB: Inhibins and activins inhibit and activate, respectively, the secretion of follitropin by the pituitary gland. Inhibins/activins are involved in regulating a number of diverse functions such as hypothalamic and pituitary hormone secretion, gonadal hormone secretion, germ cell development and maturation, erythroid differentiation, insulin secretion, nerve cell survival, embryonic axial development or bone growth, depending on their subunit composition. Inhibins appear to oppose the functions of activins. Belongs to the TGF-beta family.

Protein type: Cytokine; Secreted, signal peptide; Secreted; Cell development/differentiation

Chromosomal Location of Human Ortholog: 2cen-q13

Cellular Component: extracellular space; perinuclear region of cytoplasm; extracellular region

Molecular Function: protein binding; protein homodimerization activity; growth factor activity; hormone activity; cytokine activity; transforming growth factor beta receptor binding; host cell surface receptor binding

Biological Process: fat cell differentiation; activin receptor signaling pathway; defense response; negative regulation of hepatocyte growth factor biosynthetic process; cellular response to starvation; negative regulation of follicle-stimulating hormone secretion; negative regulation of insulin secretion; regulation of apoptosis; ovarian follicle development; cellular response to insulin stimulus; response to mechanical stimulus; regulation of MAPKKK cascade; positive regulation of follicle-stimulating hormone secretion; cell differentiation; cell development; oocyte development; growth