ACVR2B

(redirected from ActRIIB)
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ACVR2B

A gene on chromosome 3p22 that encodes activin receptor type IIB, a receptor that forms a complex with other type-I and two type-II  transmembrane serine/threonine kinase receptors for activin, a dimeric growth and differentiating factor belonging to the TGF-beta superfamily of structurally related signalling proteins. Type-I receptors are essential for signalling; type-II receptors are required for binding ligands and expression of type-I receptors. After activin binding, type-I receptors phosphorylate cytoplasmic SMAD transcription factors, which then translocate to the nucleus and interact directly with DNA or in complex with other transcription factors, playing roles in cell differentiation, growth arrest and apoptosis.
References in periodicals archive ?
We recently identified two ActRIIB paralogs in the marine fish gilthead sea bream Sparus aurata Linnaeus, 1758: ActRIIB-1 and ActRIIB-2 (with two alleles: 2a and 2b) (Funkenstein et al., 2012).
For comparative studies of the biological activities of the two ActRIIB paralogs, clone #1 of saActRIIB-l-ECD/pPICZ[alpha]A was expressed and purified essentially as described above for saActRIIB-2a-ECD/pPICZaA.
However, both ECDs were effective in inhibiting MSTN and activin A, which suggests that both ActRIIB paralogs act in a similar way to mammalian peptides.
In the present study, we describe the expression, purification, and biological activity of the soluble form of the second paralog of ActRIIB found in fish: ActRIIB-2a-ECD.
Most likely, they sequester MSTN and activin away from full-length, membrane-bound ActRIIB. Earlier studies in mammals, in which direct binding assays of soluble ActRII and ActRIIB to radiolabeled activins and inhibins were tested, revealed that both receptors bind activin A with high affinity (del Re et al., 2004).
A detailed kinetic characterization of soluble ActRIIB binding to several low- and high-affinity ligands demonstrated that both MSTN and GDF-11 bind ActRIIB-ECD with affinities comparable to those of activin A (Sako et al., 2010).
Number and position of amino acid residues in mouse ActRIIB, shown earlier to be directly involved in binding to activin (Gray et al., 2000); Thompson et al., 2003), are also conserved in saActRIIB-l-ECD and saActRIIB-2a-ECD.
The collaboration will initially investigate ACE-031, Acceleron's lead ActRIIB drug candidate, currently in a Phase IIa trial for the treatment of patients with Duchenne Muscular Dystrophy (DMD).