Isolation and characterization of a novel, human neuronal nitric oxide synthase cDNA.

A splice variant of nNOS has recently been identified in both rat and mouse which contains an in-frame insertion of 34 conserved amino acids between the N-terminal oxygenase and the C-terminal reductase domains. In the present study we report the isolation and characterization of a similar, but not identical (76% amino acid identity), human variant (nNOSmu) which arises from the splicing in of an additional exon between exons 16 and 17 of the human nNOS gene. Furthermore, we describe two additional splice variants which, if translated, would give rise to truncated forms of nNOS lacking the C-terminal reductase domain. These additional variants and nNOSmu; have a distinct and more restricted expression pattern compared to nNOS. Further studies are required to elucidate the possible physiological roles of these novel human nNOS splice variants in NO signaling.