STRUCTURAL ORGANIZATION OF THE HUMAN OXYTOCIN RECEPTOR GENE

We isolated and charactarized the human oxytocin receptor gene, Southe rn blots indicated that the human genome has a single copy of the gene , Chromosomal localization by fluorescence in situ hybridization also showed that the gene was a single copy, assigned to 3p26,2 of the huma n chromosome, The gene spans approximately 17 kilobases and contains 3 introns and 4 exons, Exons 1 and 2 correspond to the 5'-non-coding re gion, followed by exons 3 and 4 encoding the amino acids of the recept or, Intron 3, which is the largest at 12 kilobases, separates the codi ng region immediately after the putative sixth transmembrane-spanning domain. The transcription start sites, demonstrated by primer extensio n analysis, lie 618 and 621 base pairs upstream of the methionine init iation codon, Near these putative transcription start sites, we found a TATA-like motif and a potential SP-l binding site at about 30 and 65 base pairs, respectively. We also found other known binding sites of transcription regulating factors, such as AP-1, AP-2, GATA-1, Myb, nuc leofactor-interleukin 6 binding consensus sequence, and an acute phase reactant-responsive element. No estrogen-responsive element was obser ved except three half-palindromic estrogen-responsive element motifs. Our findings of the oxytocin receptor gene structure should help to el ucidate the mechanism by which the gene expression is induced drastica lly at parturition in the uterus and how the gene is regulated in othe r organs such as the mammary gland or central nervous system.