{"symbol":"ACVR2B","synonyms":["ACTRIIB","ACTR-IIB","HTX4"],"name":"activin A receptor, type IIB","description":"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 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 for 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. Type II receptors are considered to be constitutively active kinases. This gene encodes activin A type IIB receptor, which displays a 3- to 4-fold higher affinity for the ligand than activin A type II receptor. [provided by RefSeq, Jul 2008]","ncbiEntrezGeneId":93,"ncbiEntrezGeneUrl":"http://www.ncbi.nlm.nih.gov/gene/93","proteins":[{"symbol":"AVR2B_HUMAN","href":"/api/1.0/protein/AVR2B_HUMAN"}],"hgncRootFamilies":[{"name":"Receptor kinases","href":"/api/1.0/gene_family/Receptor+kinases"}]}