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Conservation of promoter, coding and intronic regions of the non‐classical MHC class II DYA gene suggests evolution under functional constraints
Author(s) -
Ballingall K. T.,
McKeever D. J.
Publication year - 2005
Publication title -
animal genetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.756
H-Index - 81
eISSN - 1365-2052
pISSN - 0268-9146
DOI - 10.1111/j.1365-2052.2005.01281.x
Subject(s) - biology , pseudogene , genetics , gene , exon , major histocompatibility complex , open reading frame , coding region , negative selection , conserved sequence , alternative splicing , mhc class i , intron , peptide sequence , genome
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‐DY α 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.