激活素是属于结构相关信号蛋白转化生长因子β（TGFβ）超家族的二聚生长和分化因子。激活素通过受体丝氨酸激酶的异聚体复合物传递信号，该复合物包括至少两个I型（I和IB）和两个II型（II和IIB）受体。这些受体都是跨膜蛋白，由一个与富含半胱氨酸区域结合的配体胞外结构域、一个跨膜结构域和一个具有预测丝氨酸/苏氨酸特异性的胞质结构域组成。I型受体对于信号传导是必需的；II型受体对于结合配体和I型受体的表达是必需的。I型和II型受体在配体结合后形成稳定的复合物，导致I型受体被II型受体磷酸化。这个基因编码一个活化素I型受体，它与活化素II型受体一起发出特定的转录反应信号。该基因突变与进行性纤维发育异常骨化相关。
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. This gene encodes activin A type I receptor which signals a particular transcriptional response in concert with activin type II receptors. Mutations in this gene are associated with fibrodysplasia ossificans progressive.