GENOMIC ORGANIZATION AND PROMOTER FUNCTION OF THE HUMAN THYROTROPIN-RELEASING-HORMONE RECEPTOR GENE

We isolated and characterized the gene for the human thyrotropin-relea sing hormone receptor, The gene spanned more than 30 kilobases and con tained three exons and two introns, Intron 1 exists in the 5'-untransl ated region, and intron 2 is more than 25 kilobases in length which in terrupts the coding region before the beginning of the putative sixth transmembrane domain. Exon 3 encodes the rest of the coding region and the entire 3'-untranslated region. The 3'-flanking region contains fo ur potential polyadenylation signals, and 3'-rapid amplification of cD NA ends studies showed that only a signal at 2076 base pairs downstrea m of the stop codon was functional in the anterior pituitary, Primer e xtension and anchor-polymerase chain reaction studies indicated a tran scriptional start site at 344 base pairs upstream of the translational start site, The promoter region does not contain either a TATA box or a CAAT box in the appropriate location, Transient transfection study revealed significant activity of the promoter in GH4C1 cells, and the region between -338 and -933 bp from the transcriptional start site wo rked as a negative regulator, Knowledge of the genomic organization an d the promoter region of thyrotropin-releasing hormone (TRH) receptor gene will allow further studies of possible disorders of the TRH recep tor, as well as facilitate elucidation of transcriptional control of t he human TRH receptor gene.