Alternative processing of bovine growth hormone mRNA: nonsplicing of the final intron predicts a high molecular weight variant of bovine growth hormone.
We have detected a variant species of bovine growth hormone mRNA in bovine pituitary tissue and in a stably transfected bovine growth hormone-producing cell line. Analysis of this variant mRNA indicated that the last intervening sequence (intron D) had not been removed by splicing. Inspection of the sequence of intron D reveals an open reading frame through the entire intron, with a termination codon encountered 50 nucleotides into the fifth exon, which is shifted from the normal reading frame in this variant mRNA. If translated, this variant mRNA would encode a growth hormone-related polypeptide having 125 amino-terminal amino acids identical to wild-type growth hormone, followed by 108 carboxyl-terminal amino acids encoded by the 274 bases of intron D along with the first 50 nucleotides of exon 5. This variant polypeptide would be 42 amino acids longer than wild-type bovine growth hormone or approximately 5000 greater in molecular weight. The intron D-containing variant of bovine growth hormone mRNA was demonstrated to exist on polysomes, suggesting that this mRNA species is translated into a polypeptide. Cytosolic mRNA species containing any of the other three introns of the bovine growth hormone gene were not detectable.
Hampson
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Rottman
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D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002417:Cattle; D002460:Cell Line; D014644:Genetic Variation; D013006:Growth Hormone / Q000235:genetics*; D007438:Introns; D008970:Molecular Weight; D010957:Plasmids; D014176:Protein Biosynthesis; D012326:RNA Splicing; D012333:RNA, Messenger / Q000235:genetics*
D012333:RNA, Messenger; D013006:Growth Hormone