Genomic structure of the mouse δ opioid receptor gene

Using mouse δ opioid receptor (DOR) cDNA sequence to probe genomic libraries in bacteriophage λ and P1 vectors, clones traversing the entire DOR coding sequence and 5′ and 3′ flanking regions were isolated. Genomic sequence encoding mature DOR message, including 5′ and 3′ untranslated sequence, is divided by two introns of 26 kb and 3 kb, resulting in the gene occupying 32 kb of chromosomal DNA. Multiple putative transcription initiation sites were located, by RNase protection assay, in TATA-less G+C rich sequence between 390 and 140 nucleotides upstream from the ATG translation start codon. A polyadenylation site was located 1.24 kb downstream from the TGA translation stop codon. Examination of 1.3 kb of 5′ flanking sequence revealed potential binding sites for several known transcription factors including: Sp1, Ap-2, NF-κB, NF-IL6, and NGFI-B.