Activins are dimeric growth and differentiation factors which belong to the transforming growth factor-beta (TGF-beta) superfamily of structurally related signaling proteins. Activins signal through a heteromeric complex of receptor serine kinases which include at least two type I ( I and IB) and two type II (II and IIB) receptors. These receptors are all transmembrane proteins, composed of a ligand-binding extracellular domain with cysteine-rich region, a transmembrane domain, and a cytoplasmic domain with predicted serine/threonine specificity. Type I receptors are essential for signaling; and type II receptors are required for binding ligands and for expression of type I receptors. Type I and II receptors form a stable complex after ligand binding, resulting in phosphorylation of type I receptors by type II receptors. Activin A mutations are associated with fibrodysplasia ossificans progressive.
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Protein Aliases: Activin beta-A chain; EDF; erythroid differentiation factor; Erythroid differentiation protein; follicle-stimulating hormone-releasing protein; FSH-releasing protein; Inhibin beta A chain; inhibin, beta A (activin A, activin AB alpha polypeptide); Inhibin, beta-1
Gene Aliases: EDF; FRP; INHBA
Molecular Function: growth factor