Isolation and characterization of the gene encoding the a-subunit of the rat pituitary glycoprotein hormones

The gene encoding the common a subunit of the rat pituitary glycoprotein hormones was isolated from a rat genomic DNA library. The gene spans approximately 8 kb, and contains four exons and three intervening sequences of 5.4 kb, 1.1 kb and 0.6 kb. Blot hybridization of restriction enzyme digests of rat genomic DNA suggests that the a gene is present in a single copy. The coding region and 424 bp of the 5' -flanking region of the gene were sequenced. Primer extension and S l nuclease analyses revealed a single transcriptional start point downstream from consensus promoter elements. The organization of the rat a-subunit gene is similar to that of the human and bovine genes including the sizes and locations of the four exons and three introns. In addition, a region of strong sequence similarity has been identified in the 5' -flanking region of the rat, human and bovine genes. This region includes sequences which are similar to a putative triiodothyronine regulatory element and the previously identified cAMP regulatory region; such sequences may mediate the known effects of these factors on a-subunit gene expression