INOS (Tyr-1055) [conserved site], Phosphospecific Antibody

Nitric oxide synthases (NOS), the enzymes responsible for synthesis of NO, are homodimers whose monomers are themselves two fused enzymes: a cytochrome reductase and a cytochrome that requires three cosubstrates (L-arginine, NADPH, and oxygen) and five cofactors or prosthetic groups (FAD, FMN, calmodulin, tetrahydrobiopterin, and heme) . Several distinct NOS isoforms are produced from three distinct genes, inducible NOS (iNOS, NOS-II), neuronal NOS (bNOS, NOS-I), and endothelial NOS (eNOS, ecNOS, NOS-III) . The inducible form of NOS, iNOS, is Ca2+ independent and is expressed in a broad range of cell types in response to stimulation with cytokines and exposure to microbial products. Phosphorylation of iNOS may regulate its activity and stability. Src kinase-induced phosphorylation of Tyr-1055 in iNOS reduces proteasomal degradation of iNOS, leading to increased NO production. Thus, phosphorylation may be an additional control for regulating iNOS activity in response to inflammatory conditions.

The antibody detects a 130 kDa* protein corresponding to induced NOS on SDS-PAGE immunoblots of mouse macrophages treated with LPS followed by pervanadate. The antibody also detects a 150 kDa doublet that corresponds with higher molecular weight forms of NOS, which are also observed using other anti-iNOS antibodies.