Human TGF-beta  RII Isoform 2 Antibody

Most cell types express three sizes of receptors for TGF-beta. These are designated Type I (53 kDa), Type II (70-85 kDa) and Type III (250-350 kDa). The Type III receptor, a proteoglycan that exists in membrane-bound and soluble forms, binds TGF-beta 1, TGF-beta 2, and TGF-beta 3, and appears to participate in both TGF-beta dependent and independent cellular signaling. The Type II receptor, by contrast, is a membrane-bound serine/threonine kinase that binds TGF-beta 1 and TGF-beta 3 with high affinity, and TGF-beta 2 with a much lower affinity. The Type I receptor is also a membrane-bound serine/threonine kinase that requires the presence of the Type II receptor to bind TGF-beta. Evidence suggests that signal transduction requires the cytoplasmic domains of both the Type I and Type II receptors. TGF-beta receptor II isoform 2 (also TGF-beta RII isoform A) is an alternatively spliced variant of the standard Type II TGF-beta receptor (or TGF-beta RII isoform 1) that possesses a 27 amino acid substitution for Val10 near the N-terminus of the mature protein. Both TGF-beta RII and TGF-beta RII isoform 2 bind TGF-beta 1 and TGF-beta 3 with high affinity. However, only TGF-beta RII isoform 2 also binds TGF-beta 2 with high affinity in the absence of TGF-beta RIII. While TGF-beta RII is widely expressed on cells, TGF-beta RII isoform 2 shows distinct expression pattern mainly associated with bone-related cells, such as osteoblasts and mesenchymal precursor cells. TGF-beta RII isoform 2 may play an important role in TGF-beta 2 binding and signaling in cells lacking TGF-beta RIII. Mouse also expresses a TGF-beta RII isoform 2, and over aa 23-184 of this isoform, human and mouse share 80% aa sequence identity.