The genomic organisation of Oncorhynchus mykiss TGF-β has been determined through the generation of contiguous clones by PCR. The O. mykiss TGFβ 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-β 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-β genes into two exons (trout exons 6 and 7). Comparison of exon sizes in the coding region support the suggestion that the Xenopus TGF-β5 and trout TGF- β sequences are the forerunners of TGF-β1. Conservation of exons coding for the mature TGF-β peptide is relatively high (63-73% identity) but other exons show lower identities (37-58%). Comparison of the TGF-β intron sequences reveals that in general the O. mykiss introns are considerably shorter than the avian homologs. The impact of the teleost TGF-β gene organisation on theories of the gene evolution of this cytokine family are discussed.
|Number of pages||9|
|Journal||Developmental and Comparative Immunology|
|Publication status||Published - 1 Mar 1999|
- Gene organisation
- Rainbow trout
- Splice sites