Genomic structure of the human Ah receptor nuclear translocator gene (hARNT).

The vertebrate basic helix-loop-helix/Per-ARNT-Sim (bHLH/PAS protein) ARNT (aryl hydrocarbon receptor nuclear translocator) plays a crucial role in transcriptional regulation as the common subunit of a number of transcriptionally active complexes. Several studies indicate that ARNT might be involved in the pathogenesis of various genetic diseases. In this study we provide the first report on the genomic structure of the human ARNT gene (hARNT). Human BAC and PAC libraries were screened, and clones positive for ARNT were mapped, subcloned, and sequenced. The gene has an overall size of about 65 kb and consists of 22 exons varying in size from 25 to 214 bp. Splice junctions follow the GT/AG consensus except for intron 11 starting with GC at its 5' end. Knowledge of exon-intron boundaries and intronic sequences neighboring the exons allows the extended search for polymorphisms and variants in human genomic DNA. The exonintron arrangement is highly similar to the murine arnt gene (marnt) except for a slight shift in the last three exons. 5' RACE indicated several transcription start sites, one of them identical with the major transcription start site of marnt.