NOS (nitric oxide synathase) is a mediator of NO (nitric oxide) production, an inorganic gaseous messenger between cells. In cells, NOS catalyzes the oxidization of L-arginine to produce L-citrulline and NO. Three isoforms of NOS has been identified (eNOS, iNOS, and nNOS) with all of them having binding sites for NADPH, FAD, FMN, and tetrahydrobiopterin (1). Specifically, nNOS (Neuronal nitric oxide synthase bNOS, cNOS, Type I) is bound to PSD95 located in the neuronal membrane and at increased level of Ca2+, nNOS is trasnlocated to cytoplasm. In cytoplasm, nNOS is dephosphorylated by calcineurin which initiates NO production (2). A phosphorylation by PKA and PKC on nNOS leads down-regulation of NO production.

WB, IHC, IP, FC