A total of three members of the TGFβ family, TGFβ1, TGFβ2 and TGFβ3, have been identified in mammals. Each is synthesized as a latent precursor that is subsequently cleaved forming the 112 amino acid growth factor which becomes active upon dimerization. TGFβs mediate their activity by high affinity binding to the type II receptor transmembrane protein with a cytoplasmic serine-threonine kinase domain. TGFβ RIII (transforming growth factor beta receptor type 3), also known as TGFBR3 or TGFR-3, is an 850 amino acid secreted and single-pass type I membrane protein that contains one ZP domain and may assist in capturing TGFβ for presentation to signaling receptors. TGFβ RIII undergoes post-translational modification by glycosaminoglycan groups (GAG) and is encoded by a gene that maps to human chromosome 1p22.2.
