Activin receptor type-1B is a protein that in humans is encoded by the ACVR1Bgene.[5][6]
ACVR1B or ALK-4 acts as a transducer of activin or activin-like ligands (e.g., inhibin) signals. Activin binds to either ACVR2A or ACVR2B and then forms a complex with ACVR1B. These go on to recruit the R-SMADsSMAD2 or SMAD3.[7] ACVR1B also transduces signals of nodal, GDF-1, and Vg1; however, unlike activin, they require other coreceptor molecules such as the protein Cripto.[8]
Function
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 a 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 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 IB receptor, composed of 11 exons. Alternative splicing and alternative polyadenylation result in 3 fully described transcript variants. The mRNA expression of variants 1, 2, and 3 is confirmed, and a potential fourth variant contains an alternative exon 8 and lacks exons 9 through 11, but its mRNA expression has not been confirmed.[6]
^ abDe Winter JP, De Vries CJ, Van Achterberg TA, Ameerun RF, Feijen A, Sugino H, De Waele P, Huylebroeck D, Verschueren K, Van Den Eijden-Van Raaij AJ (May 1996). "Truncated activin type II receptors inhibit bioactivity by the formation of heteromeric complexes with activin type I. receptors". Exp. Cell Res. 224 (2): 323–34. doi:10.1006/excr.1996.0142. PMID8612709.
De Winter JP, De Vries CJ, Van Achterberg TA, Ameerun RF, Feijen A, Sugino H, De Waele P, Huylebroeck D, Verschueren K, Van Den Eijden-Van Raaij AJ (1996). "Truncated activin type II receptors inhibit bioactivity by the formation of heteromeric complexes with activin type I. receptors". Exp. Cell Res. 224 (2): 323–34. doi:10.1006/excr.1996.0142. PMID8612709.
Röijer E, Miyazono K, Aström AK, Geurts van Kessel A, ten Dijke P, Stenman G (1998). "Chromosomal localization of three human genes encoding members of the TGF-beta superfamily of type I serine/threonine kinase receptors". Mamm. Genome. 9 (3): 266–8. doi:10.1007/s003359900745. PMID9501322. S2CID21839781.
Hashimoto O, Yamato K, Koseki T, Ohguchi M, Ishisaki A, Shoji H, Nakamura T, Hayashi Y, Sugino H, Nishihara T (1998). "The role of activin type I receptors in activin A-induced growth arrest and apoptosis in mouse B-cell hybridoma cells". Cell. Signal. 10 (10): 743–9. doi:10.1016/S0898-6568(98)00021-7. PMID9884026.
