Av. Hall et al., STRUCTURAL ORGANIZATION OF THE HUMAN NEURONAL NITRIC-OXIDE SYNTHASE GENE (NOS1), The Journal of biological chemistry, 269(52), 1994, pp. 33082-33090
Neuronal nitric oxide (NO) synthase, localized to human chromosome 12,
uniquely participates in diverse biologic processes; neurotransmissio
n, the regulation of body fluid homeostasis, neuroendocrine physiology
, control of smooth muscle motility, sexual function, and myocyte/myob
last biology, among others. Restriction enzyme mapping, subcloning, an
d DNA sequence analysis of bacteriophage- and yeast artificial chromos
ome-derived human genomic DNA indicated that the mRNA for neuronal NO
synthase is dispersed over a minimum of 160 kilobases of human genomic
DNA. Analysis of intron-exon splice junctions predicted that the open
reading frame is encoded by 28 exons, with translation initiation and
termination in exon 2 and exon 29, respectively. Determination of tra
nscription initiation sites in brain poly(A) RNA with primer extension
analysis and RNase protection revealed a major start site 28 nucleoti
des downstream from a TATA box. Sequence inspection of 5'-flanking reg
ions revealed potential cis-acting DNA elements: AP-2, TEF-1/MCBF, CRE
B/ATF/c-Fos, NRF-1, Ets, NF-1, and NF-kappa B-like sequences. Diversit
y appears to represent a major theme apparent upon analysis of human n
euronal NO synthase mRNA transcripts. A microsatellite of the dinucleo
tide variety was detected within the S'-untranslated region of exon 29
. Multiple alleles were evident in normal individuals indicating the e
xistence of allelic mRNA sequence variation. Characterization of varia
nt human neuronal NO synthase cDNAs indicated the existence of casette
exon 9/10 and exon 10 deletions as examples of structural mRNA divers
ity due to alternative splicing. The latter deletion of a 175-nucleoti
de exon introduces a frameshift and premature stop codon indicating th
e potential existence of a novel NH2 terminus protein. In summary, ana
lysis of the human neuronal NO synthase locus reveals a complex genomi
c organization and mRNA diversity that is both allelic and structural.