FIG. 1.

Protein structure of nitric oxide synthase 3 (NOS3) and NOS1 splice variants. All NOSs include an oxygenase and a reductase domain and a calmodulin (CaM) binding site. The oxygenase moiety contains the L-arginine, heme, and tetrahydrobiopterin (BH4)-binding domains; whereas the reductase moiety contains the flavin mononucleotide (FMN), flavin adenine dinucleotide (FAD), and nicotinamide adenine dinucleotide phosphate (NADPH)- binding domains. An additional PDZ domain is found in the N-terminal of the α,μ-NOS1 and NOS1–2 variants and allows the enzyme to bind other proteins with a similar structure. aa, aminoacids. (To see this illustration in color, the reader is referred to the web version of this article at www.liebertpub.com/ars).