Structural characterization of the human estrogen synthetase (aromatase) gene

The estrogen synthetase (aromatase, cytochrome P-450AROM) gene has been isolated from human genomic libraries and characterized. The restriction map of 43 positive clones obtained indicated that this enzyme is present as a single copy gene. The aromatase gene is unexpectedly large compared with other forms of the cytochrome P-450 superfamily, spanning at least 70 kilobases. The gene consists of 10 exons and its 5'-untranslated region is divided into 2 exons by an intron of more than 35 kilobases long. This organization of the first exon in the aromatase gene is unique in the cytochrome P-450 superfamily. All the exon-intron junctional sequences conform to the canonical GT/AG rule. The sequences of a TATA box and a CAAT box are present 27 and 83 base pairs upstream from the transcriptional initiation site. Within 3 kilobases upstream from the initiation site, there are no typical consensus sequences of responsive elements for glucocorticoid and c-AMP, which regulate aromatase expression.