Linked Life Data

1730884

Source:http://linkedlifedata.com/resource/pubmed/id/1730884

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
1992-2-19
pubmed:abstractText
The evolution of the Ag-binding site of polymorphic class II molecules was investigated by comparing the pattern of silent and replacement substitutions in the first domain exon of DQB and DRB alleles in two distantly related mammalian species, man and cattle. We show that the first domain can be subdivided into two regions, corresponding to the beta-strand and alpha-helical regions, with distinct evolutionary histories. The data for the alpha-helical region are in conflict with the standard phylogeny of mammalian class II genes. In this region, there is only weak locus divergence at the protein level and the frequency of silent substitutions is extremely low between nonorthologous genes (i.e., DQB-DRB) within species. We propose that the major underlying cause for the observed sequence similarity in the alpha-helical region is due to a selective constraint restricting the sequence divergence at the protein level. This selective constraint may be related to the interaction between different isotypic forms of polymorphic class II beta-chains and a common ligand. The extremely low frequencies of silent substitutions between nonorthologous genes within species are most likely due to the transfer of sequence information between loci by the occurrence of gene conversion-like events in the particular gene segment.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
AIM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Feb
pubmed:issn
0022-1767
pubmed:author
pubmed:issnType
Print
pubmed:day
1
pubmed:volume
148
pubmed:geneSymbol
HLA-DQB2, HLA-DQBQ, HLA-DRB3
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
968-73
pubmed:dateRevised
2011-11-17
pubmed:meshHeading
pubmed:year
1992
pubmed:articleTitle
Exon encoding the antigen-binding site of MHC class II beta-chains is divided into two subregions with different evolutionary histories.
pubmed:affiliation
Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences, Uppsala.
pubmed:publicationType
Journal Article, Comparative Study, Research Support, Non-U.S. Gov't