title: Paired opposing leukocyte receptors recognizing rapidly evolving ligands are subject to homogenization of their ligand binding domains.
abstract: Some leukocyte receptors come in groups of two or more where the partners share ligand(s) but transmit opposite signals. Some of the ligands, such as MHC class I, are fast evolving, raising the problem of how paired opposing receptors manage to change in step with respect to ligand binding properties and at the same time conserve opposite signaling functions. An example is the KLRC (NKG2) family, where opposing variants have been conserved in both rodents and primates. Phylogenetic analyses of the KLRC receptors within and between the two orders show that the opposing partners have been subject to post-speciation gene homogenization restricted mainly to the parts of the genes that encode the ligand binding domains. Concerted evolution similarly restricted is demonstrated also for the KLRI, KLRB (NKR-P1), KLRA (Ly49), and PIR receptor families. We propose the term merohomogenization for this phenomenon and discuss its significance for the evolution of immune receptors.
authors: Department of Anatomy, Institute of Basic Medical Sciences, University of Oslo, Blindern, Norway. sigbjorn.fossum@medisin.uio.no
authors: Sigbjørn
authors: S
authors: Fossum
authors: Per Christian
authors: PC
authors: Saether
authors: John Torgils
authors: JT
authors: Vaage
authors: Michael Rory
authors: MR
authors: Daws
authors: Erik
authors: E
authors: Dissen
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D019143:Evolution, Molecular; D000882:Haplorhini; D015395:Histocompatibility Antigens Class I / Q000276:immunology; D006801:Humans; D007113:Immunity, Innate; D007694:Killer Cells, Natural / Q000276:immunology / Q000378:metabolism; D037181:Lectins, C-Type / Q000276:immunology*; D007962:Leukocytes / Q000378:metabolism; D008024:Ligands; D051379:Mice; D008810:Mice, Inbred C57BL; D055654:NK Cell Lectin-Like Receptor Subfamily C / Q000737:chemistry / Q000235:genetics* / Q000276:immunology / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D051381:Rats; D011971:Receptors, Immunologic / Q000737:chemistry / Q000235:genetics / Q000276:immunology* / Q000378:metabolism*; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA
chemical_list: D015395:Histocompatibility Antigens Class I; D037181:Lectins, C-Type; D008024:Ligands; D055654:NK Cell Lectin-Like Receptor Subfamily C; D011971:Receptors, Immunologic