Analysis of the Organization and Nucleotide Sequence of the Chromosomal Gene for the β-Subunit of Rat Thyrotropin

The gene for the beta-subunit of rat thyrotropin has been isolated from a library of rat DNA fragments cloned in bacteriophage lambda. The complete nucleotide sequence of the gene has been determined including a portion of 5'- and 3'-flanking regions. The rat TSH-beta gene contains approximately 4879 nucleotides which ultimately lead to the production of a mRNA of about 554 nucleotides, exclusive of the 3' poly(A) tract. The first exon which represents only 5' untranslated sequences of the mRNA, is separated from the second exon by a very large, 3.9-kbp intervening sequence. The second and third exons are separated by a small, 377-bp intervening sequence. Southern blot analysis of total genomic DNA demonstrated that the rat genome contains sequences similar to the cloned gene, suggesting that no rearrangements occurred during the cloning process.