Produces nitric oxide (NO) which is a messenger molecule with diverse functions throughout the body. Involved in the induction of immune gene expression. H(+) + 2 L-arginine + 3 NADPH + 4 O2 = 4 H2O + 2 L-citrulline + 3 NADP(+) + 2 nitric oxide Binds 1 FAD. Binds 1 FMN. Expression is dependent on and stimulated by NADPH, calcium, BH4 and calmodulin. The activity is not dependent on FAD and is not stimulated by its presence. Constitutively expressed at a low level in the larval fat body, hemocyte, Malpighian tubule, midgut, silk gland and adult antenna. Induced strongly in the fat body by lipopolysaccharide (LPS). Belongs to the NOS family.