Activin A (INHBA) Active Protein

The inhibin beta A 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 tumor-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 A subunit forms a homodimer, activin A, and also joins with a beta B subunit to form a heterodimer, activin AB, both of which stimulate FSH secretion. Finally, it has been shown that the beta A subunit mRNA is identical to the erythroid differentiation factor subunit mRNA and that only one gene for this mRNA exists in the human genome. [provided by RefSeq, Jul 2008]

INHBA: 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: Secreted; Secreted, signal peptide

Chromosomal Location of Human Ortholog: 7p15-p13

Cellular Component: extracellular region

Molecular Function: identical protein binding; protein binding; growth factor activity; protein heterodimerization activity; peptide hormone binding; hormone activity; cytokine activity; transforming growth factor beta receptor binding

Biological Process: positive regulation of transcription, DNA-dependent; positive regulation of cellular protein metabolic process; activin receptor signaling pathway; mesodermal cell differentiation; defense response; palate development; negative regulation of interferon-gamma biosynthetic process; negative regulation of cell cycle; odontogenesis; negative regulation of cell proliferation; cell surface receptor linked signal transduction; ovarian follicle development; cell-cell signaling; hair follicle development; erythrocyte differentiation; cell cycle arrest; cell differentiation; negative regulation of B cell differentiation; hemoglobin biosynthetic process; response to drug; nervous system development; regulation of follicle-stimulating hormone secretion; positive regulation of erythrocyte differentiation; male gonad development; progesterone secretion; negative regulation of follicle-stimulating hormone secretion; regulation of transcription from RNA polymerase II promoter; negative regulation of macrophage differentiation; regulation of MAPKKK cascade; negative regulation of phosphorylation; positive regulation of transcription from RNA polymerase II promoter; hemopoietic progenitor cell differentiation; negative regulation of cell growth; positive regulation of follicle-stimulating hormone secretion; cell development; growth; G1/S transition of mitotic cell cycle