Activin receptor type-2A (ACVR2A) is also known as activin receptor type IIA, ACTR-IIA, ACTRIIA, and ACVR2, and is a single-pass type I membrane protein. ACVR2A belongs to the protein kinase superfamily, the TKL Ser/Thr protein kinase family, and the TGFB receptor subfamily. Upon ligand binding, ACVR2A forms a receptor complex consisting of two type II and two type I transmembrane serine/threonine kinases. Type II receptors phosphorylate and activate type I receptors, which then phosphorylate and activate SMAD transcriptional regulators. ACVR2A also serves as a receptor for activin A, activin B, and inhibin A (the latter in complex with betaglycan). Two type II activin receptors (ACVR2A and ACVR2B) have been identified, which bind different activins with distinct affinities.