Activin receptor type-1B is aprotein that in humans is encoded by theACVR1Bgene.[5][6]
ACVR1B orALK-4 acts as a transducer ofactivin or activin-like ligands (e.g.,inhibin) signals. Activin binds to eitherACVR2A orACVR2B and then forms a complex with ACVR1B. These go on to recruit theR-SMADsSMAD2 orSMAD3.[7] ACVR1B also transduces signals ofnodal,GDF-1, andVg1; however, unlike activin, they require other coreceptor molecules such as the proteinCripto.[8]
Activins are dimeric growth and differentiation factors which belong to thetransforming 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 inphosphorylation 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]
^Inman GJ, Nicolás FJ, Callahan JF, Harling JD, Gaster LM, Reith AD, Laping NJ, Hill CS (2002). "SB-431542 is a potent and specific inhibitor of transforming growth factor-beta superfamily type I activin receptor-like kinase (ALK) receptors ALK4, ALK5, and ALK7".Mol. Pharmacol.62 (1):65–74.doi:10.1124/mol.62.1.65.PMID12065756.S2CID15185199.
^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.
