The gene encoding the beta-subunit of rat luteinizing hormone. Analysis of gene structure and evolution of nucleotide...

The nucleotide sequence of the gene encoding the beta-subunit of rat luteinizing hormone (LH beta) has been determined from a genomic DNA fragment cloned in lambda phage Charon 4A. Blot hybridization of restriction enzyme digests of rat genomic DNA indicates that the gene is present in a single copy. The transcriptional unit is 0.98 kilobase in size and contains three exons interrupted by two introns of 245 and 225 base pairs (bp). The locations of the exon/intron junctions at amino acid codons -16/-15 and +41/+42 have been conserved between the rat LH beta gene and the related genes, human LH beta and human chorionic gonadotropin beta. Using S1 nuclease mapping and oligonucleotide-primed reverse transcription of ovariectomized rat pituitary mRNA, the start of transcription was determined to be 7 bp upstream from the start of translation. Characteristic promoter elements are present in the 5'-flanking region of the gene, including the Goldberg-Hogness sequence, TATAAA, 31 bp, and the consensus CAAT box sequence, 167 bp upstream from the start of transcription, respectively. Within the proximal 200 bp flanking the 5'-region of the transcriptional unit, there is strong homology between the rat and human LH beta genes, suggesting that these regions include sequences which may be important for regulation of gene expression. Isolation and characterization of the rat LH beta gene further defines the evolution of glycoprotein hormone genes and will facilitate the study of cellular and molecular mechanisms which regulate LH beta gene expression.