The O72-670 monoclonal antibody specifically binds to the Smad2 protein phosphorylated at the Ser465/467 sites and the Smad3 protein phosphorylated at the Ser423/425 sites. Smad2 and Smad3 are members of the Smad superfamily with observed molecular weights of 60 kDa and 52 kDa, respectively. The Smad family consists of three subfamilies: receptor regulated Smads or R-Smads, including Smads1, 2, 3, 5, and 8; common partner Smad, or Co-Smad, including Smad4; and inhibitory Smads, or I-Smad, including Smads 6 and 7. Activation of TGF-beta superfamily serine/threonine kinase receptors, such as TGF-beta, activin and BMP receptors, by their bound ligands leads to the phosphorylation of R-Smads at several sites. It has been shown that the ligand-bound TGF-beta type I receptor directly phosphorylates Ser465 and Ser467 of Smad2 and Ser423 and Ser425 of Smad3. Phosphorylated R-Smads form complexes with Co-Smad and translocate into the nucleus to regulate transcription affecting a wide range of critical cellular processes including cell-fate determination, proliferation, morphogenesis, differentiation and apoptosis. The inhibitory Smads inhibit this pathway through two potential mechanisms: either by preventing R-Smads from binding to their corresponding receptors and/or by competing with Smad4, the Co-Smad, from binding to R-Smads. High level expression of phosphorylated Smad2 has been associated with poor prognosis in late stage gastric carcinoma. Roles for Smad2 have been described in thymopoiesis and the TGF-β-mediated induction of regulatory T cells and Th17 cells. The specificity of the O72-670 mAb was confirmed by Western blot and immunohistochemistry using unconjugated antibody.
This antibody is conjugated to BD Horizon™ PE-CF594, which has been developed exclusively by BD Biosciences as a better alternative to PE-Texas Red®. PE-CF594 excites and emits at similar wavelengths to PE-Texas Red® yet exhibits improved brightness and spectral characteristics. Due to PE having maximal absorption peaks at 496 nm and 564 nm, PE-CF594 can be excited by the blue (488-nm), green (532-nm) and yellow-green (561-nm) lasers and can be detected with the same filter set as PE-Texas Red® (eg 610/20-nm filter).