ENOS (Ser-632), Phosphospecific Antibody

Nitric oxide (NO) has a broad range of biological activities and is implicated in signaling pathways in phylogenetically diverse species. 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. The inducible form of NOS, iNOS (NOS-II), is Ca2+ independent and is expressed in a broad range of cell types, and two constitutive Ca2+/CaM-dependent forms of NOS: nNOS (bNOS, NOS-I) identified in neurons and eNOS (ecNOS, NOS-III) identified in endothelial cells. Regulation of eNOS activity occurs through phosphorylation at multiple sites. Phosphorylation of Ser-633 (mouse Ser-632) in the FMN binding domain increases eNOS activity and may be important for the maintenance of NO synthesis after initial activation by Ca2+ flux and Ser-1177 phosphorylation.

Clone M232 was generated from a Phospho-eNOS (Ser-632) synthetic peptide (coupled to carrier protein) corresponding to amino acids surrounding Ser-632 in mouse eNOS.

The antibody detects a 140 and 120 kDa* bands on SDS-PAGE immunoblots of human umbilical vein endothelial cells, but these bands are not observed after lambda phosphatase treatment. The 120 kDa band may be a truncated form of eNOS. This sequence is conserved in human (Ser-633) and rat (Ser-632) eNOS, and has low homology to other NOS family members.