Nitric Oxide Synthase (NOS) produces Nitric Oxide (NO) Authored: Akkerman, JW, 2009-06-03 EC Number: 1.14.13.39 Edited: Jupe, S, 2010-06-07 Nitric oxide synthase (NOS) produces NO from L-arginine. There are three isoforms of NOS, endothelial, neuronal and inducible (eNOS, nNOS, and iNOS). eNOS and nNOS are constitutively expressed while iNOS is induced by immunostimulatory signals. The constitutive isoforms are regulated in vivo by the binding of calcium and calmodulin. NO produced by NOS acts as a signalling molecule by diffusing across cell membranes to activate soluble guanylate cyclase (sGC). Pubmed19089323 Reactome Database ID Release 43418436 Reactome, http://www.reactome.org ReactomeREACT_23872 Reviewed: Kunapuli, SP, 2010-06-07