Conservation of promoter, coding, and intronic regions of the non-classical MHC class II DYA gene suggests evolution under functional constraints

The major histocompatibility complex (MHC) in ruminants contains a unique pair of class II genes (DYA and DYB) of unknown function. As functional genes show higher levels of nucleotide conservation than pseudogenes we compared the DYA genes from sheep and cattle, two species which diverged from a co...

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Bibliographic Details
Published in:Animal genetics 2005-06, Vol.36 (3), p.237-239
Main Authors: Ballingall, K.T, McKeever, D.J
Format: Article
Language:English
Subjects:
alternative splicing
Amino Acid Sequence
amino acid sequences
Animals
Base Sequence
Bos
bovine
cattle
Cattle - genetics
class II DYA
Conserved Sequence - genetics
DNA Primers
evolution
Evolution, Molecular
Exons - genetics
food animals
genes
Genetic Variation
Histocompatibility Antigens Class II - genetics
introns
Introns - genetics
major histocompatibility complex
messenger RNA
Molecular Sequence Data
natural selection
nucleotide sequences
open reading frames
ovine
Ovis
polypeptides
promoter
promoter regions
Promoter Regions, Genetic - genetics
Selection, Genetic
Sequence Alignment
Sequence Analysis, DNA
sheep
Sheep - genetics
Species Specificity
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Summary:The major histocompatibility complex (MHC) in ruminants contains a unique pair of class II genes (DYA and DYB) of unknown function. As functional genes show higher levels of nucleotide conservation than pseudogenes we compared the DYA genes from sheep and cattle, two species which diverged from a common ancestor approximately 20 million years ago. Comparative analysis identified levels of nucleotide conservation in immediate promoter (97%), coding (94%) and intronic regions (91%) comparable with functional MHC genes. The Ovar-DYA transcript revealed an open reading frame encoding a 288 amino acid protein compared with a 253 amino acid protein associated with the BoLA-DYA transcript. A dinucleotide deletion in exon 4 of the Ovar-DYA transcript combined with alternative exon 5 splice sites introduces unusual diversity to the cytoplasmic domain of the Ovar-DYalpha polypeptide. The degree of conservation between these class II MHC genes is consistent with evolution under purifying selection suggesting that these genes retain a unique function in ruminants.
ISSN:0268-9146
1365-2052
DOI:10.1111/j.1365-2052.2005.01281.x