Activin A Receptor Type I B (ACVR1B)

ACVR1B acts as a transducer of Activin or activin like ligands signals. Activin binds to either ACVR2A or ACVR2B and then forms a complex with ACVR1B. These go on to recruit the R-SMADs SMAD2 or SMAD3.ACVR1B also transduces signals of nodal, GDF-1, and Vg1; however, unlike activin, they require other coreceptor molecules such as the protein Cripto.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 and two type II receptors. several truncated ACVR1B receptor isoforms are exclusively expressed in human pituitary tumors, and that the majority of such tumors did not exhibit activin-induced growth arrest in culture.