title: Genomic organisation of rainbow trout, Oncorhynchus mykiss TGF-beta.
abstract: The genomic organisation of Oncorhnchus mykiss TGF-beta has been determined through the generation of contiguous clones by PCR. The O. mykiss TGF-beta gene is approximately 3.4 Kb in length and consists of 7 coding exons with no introns in the 5'-UTR. Whilst this is the same number of exons found in TGF-beta genes of amphibians, birds and mammals, in the O. mykiss gene intron 2 of other vertebrates is absent and an additional intron is present at the 3' end of the molecule, splitting exon 7 of the other known TGF-beta genes into two exons (trout exons 6 and 7). Comparison of exon sizes in the coding region support the suggestion that the Xenopus TGF-beta5 and trout TGF-beta sequences are the forerunners of TGF-beta1. Conservation of exons coding for the mature TGF-beta peptide is relatively high (63-73% identity) but other exons show lower identities (37-58%). Comparison of the TGF-beta intron sequences reveals that in general the O. mykiss introns are considerably shorter than the avian homologs. The impact of the teleost TGF-beta gene organisation on theories of the gene evolution of this cytokine family are discussed.
authors.affiliation: Department of Zoology, University of Aberdeen, Scotland, UK.
authors.forename: G D
authors.initials: GD
authors.lastname: Daniels
authors.forename: C J
authors.initials: CJ
authors.lastname: Secombes
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D018076:DNA, Complementary; D005091:Exons; D006801:Humans; D007438:Introns; D008969:Molecular Sequence Data; D017686:Oncorhynchus mykiss / Q000235:genetics* / Q000276:immunology; D017386:Sequence Homology, Amino Acid; D016212:Transforming Growth Factor beta / Q000235:genetics*
chemical_list: D018076:DNA, Complementary; D016212:Transforming Growth Factor beta