Nucleotide sequence of the bovine growth hormone chromosomal gene

A library of cloned bovine DNA fragments was constructed and screened for growth hormone sequences. The growth hormone gene was isolated from this library and its nucleotide sequence determined. The likely transcription initiation site was located using the S1 nuclease protection procedure. The bovine growth hormone gene contains approximately 1793 nucleotides and consists of five exons separated by four intervening sequences. The sequence TATAAA is found in the 5' flanking region and probably is involved in facilitating transcription initiation. Comparison of the bovine growth hormone gene to the known sequence of the rat and human genes reveals that the coding regions of the three genes are highly conserved. In general the intervening sequences are much less similar than the coding regions. Interestingly, all three growth hormone genes share a conserved (but nonidentical) 40 base pair region within the 5' flanking region. This conserved region may be an important sequence involved in the hormonal regulation of growth hormone gene transcription. Analysis of GH sequences present in total bovine DNA suggests that the bovine genome contains a gene similar to the cloned gene as well as a different, but related, gene. The functional significance of the two genes remains to be explored. Analysis of nuclear species of growth hormone mRNA has demonstrated the presence of RNAs of 2100, 1400 and 1000 nucleotides containing growth hormone sequences. These likely correspond to a polyadenylated primary transcript, a processing intermediate and mature growth hormone mRNA, respectively.