High polymorphism of Mhc-E locus in non-human primates: alleles with identical exon 2 and 3 are found in two different species.
Thirteen Mhc-E new sequences were found in eight individuals belonging to the Cercopithecinae family, i.e.: Macaca mulatta, Macaca fascicularis and Cercopithecus aethiops when studying E locus polymorphism. No changes were found in the invariant residues which are required for the correct conformation of the peptide presenting region which are conserved in classical Mhc class I molecules from fish and reptiles to humans; however, polymorphism of Mhc-E alleles is not limited to the three typical hypervariable regions per domain as it is in classical class I alleles. The rate of synonymous and nonsynonymous substitutions in the DNA sequence corresponding to the antigen binding site, compared to the remainder of exons 2 and 3 shows that the peptide-binding site is under high evolutionary pressure for stability since only synonymous substitutions have been found to be accepted in apes. Also, a clear example of trans-species evolution of allelism is found: two identical exon 2 and exon 3 sequences there exist belonging to individuals from different species (Mamu-Mhc-E*0101 and Mafa-Mhc-E*04). In addition, two Macaca mulatta individuals show an Mhc-E locus duplication. Finally, phylogenetic tree analysis shows that Mhc class I molecules found in Saguinus oedipus (described as Mhc-G homologues) are closer to Mhc-E sequences.
Alvarez
M
M
Department of Immunology, Hospital 12 de Octubre, Universidad Complutense, Madrid, Spain.
Martinez-Laso
J
J
Varela
P
P
Diaz-Campos
N
N
Gomez-Casado
E
E
Vargas-Alarcon
G
G
Garcia-Torre
C
C
Arnaiz-Villena
A
A
D000483:Alleles; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D002460:Cell Line; D002522:Chlorocebus aethiops / Q000235:genetics* / Q000276:immunology; D002874:Chromosome Mapping; D005091:Exons; D008252:Macaca fascicularis / Q000235:genetics* / Q000276:immunology; D008253:Macaca mulatta / Q000235:genetics* / Q000276:immunology; D008285:Major Histocompatibility Complex / Q000235:genetics*; D008969:Molecular Sequence Data; D010802:Phylogeny; D011110:Polymorphism, Genetic; D011323:Primates; D011485:Protein Binding; D012452:Saguinus / Q000235:genetics / Q000276:immunology; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid