title: A small, variable, and irregular killer cell Ig-like receptor locus accompanies the absence of MHC-C and MHC-G in gibbons.
abstract: The killer cell Ig-like receptors (KIRs) of NK cells recognize MHC class I ligands and function in placental reproduction and immune defense against pathogens. During the evolution of monkeys, great apes, and humans, an ancestral KIR3DL gene expanded to become a diverse and rapidly evolving gene family of four KIR lineages. Characterizing the KIR locus are three framework regions, defining two intervals of variable gene content. By analysis of four KIR haplotypes from two species of gibbon, we find that the smaller apes do not conform to these rules. Although diverse and irregular in structure, the gibbon haplotypes are unusually small, containing only two to five functional genes. Comparison with the predicted ancestral hominoid KIR haplotype indicates that modern gibbon KIR haplotypes were formed by a series of deletion events, which created new hybrid genes as well as eliminating ancestral genes. Of the three framework regions, only KIR3DL3 (lineage V), defining the 5' end of the KIR locus, is present and intact on all gibbon KIR haplotypes. KIR2DL4 (lineage I) defining the central framework region has been a major target for elimination or inactivation, correlating with the absence of its putative ligand, MHC-G, in gibbons. Similarly, the MHC-C-driven expansion of lineage III KIR genes in great apes has not occurred in gibbons because they lack MHC-C. Our results indicate that the selective forces shaping the size and organization of the gibbon KIR locus differed from those acting upon the KIR of other hominoid species.
authors.affiliation: Department of Structural Biology, Stanford University, Stanford, CA 94305, USA.
authors.forename: Laurent
authors.initials: L
authors.lastname: Abi-Rached
authors.forename: Heiner
authors.initials: H
authors.lastname: Kuhl
authors.forename: Christian
authors.initials: C
authors.lastname: Roos
authors.forename: Boudewijn
authors.initials: B
authors.lastname: ten Hallers
authors.forename: Baoli
authors.initials: B
authors.lastname: Zhu
authors.forename: Lucia
authors.initials: L
authors.lastname: Carbone
authors.forename: Pieter J
authors.initials: PJ
authors.lastname: de Jong
authors.forename: Alan R
authors.initials: AR
authors.lastname: Mootnick
authors.forename: Florian
authors.initials: F
authors.lastname: Knaust
authors.forename: Richard
authors.initials: R
authors.lastname: Reinhardt
authors.forename: Peter
authors.initials: P
authors.lastname: Parham
authors.forename: Lutz
authors.initials: L
authors.lastname: Walter
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000940:Antigenic Variation / Q000235:genetics* / Q000276:immunology; D001483:Base Sequence; D022202:Chromosomes, Artificial, Bacterial / Q000276:immunology; D019143:Evolution, Molecular; D017353:Gene Deletion; D056426:Genetic Loci / Q000276:immunology*; D006239:Haplotypes / Q000276:immunology; D015395:Histocompatibility Antigens Class I / Q000235:genetics*; D006801:Humans; D006922:Hylobates / Q000235:genetics* / Q000276:immunology*; D007135:Immunoglobulin Variable Region / Q000235:genetics*; D008253:Macaca mulatta; D008969:Molecular Sequence Data; D002679:Pan troglodytes; D057079:Pongo; D054340:Receptors, KIR / Q000235:genetics* / Q000378:metabolism
chemical_list: D015395:Histocompatibility Antigens Class I; D007135:Immunoglobulin Variable Region; D054340:Receptors, KIR