A phylogenetic analysis of cattle DRB3 alleles with a deletion of codon 65 |
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Authors: | Sofia Mikko Harris A Lewin L Andersson |
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Institution: | (1) Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences, Box 597, S-751 24 Uppsala, Sweden, SE;(2) Laboratory of Immunogenetics, Department of Animal Sciences, University of Illinois, Urbana, Illinois, USA, US |
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Abstract: | One of the most common cattle major histocompatibility complex DRB3 alleles,
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0201, includes a deletion of codon 65 encoding one residue in the α-helical chain. The mutation is functionally interesting and
is likely to influence peptide binding. Exon 2 of two additional del65 alleles,
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3301 and
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4101, have now been sequenced with the aim to investigate the evolutionary relationship of this allelic group. Despite a fairly
large genetic distance between the three alleles (11–17 nucleotide substitutions causing 8–11 amino acid substitutions) we
found clear indications of a common ancestry. The α-helical region was very similar or identical among the alleles whereas
the β-strand region was quite divergent. The results indicated that interallelic recombination has contributed to the diversification
of the del65 group. Deletion of codon 65 has also been found in a roe deer DRB1 allele and a cattle DQB3 allele. Sequence comparisons of the cattle and roe deer DRB del65 alleles refuted the possibility of a trans-species persistence of a del65 allelic lineage but the two species may share
a short ancestral sequence motif including del65. In addition to del65, the cattle DQB3 allele did not show any striking sequence similarities to the DRB alleles.
Received: 20 March 1997 / Revised: 17 June 1997 |
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Keywords: | BdA MHC Cattle Roe deer DRB Deletion |
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