title: A novel, nonclassical MHC class I molecule specific to the common chimpanzee.
abstract: All expressed human MHC class I genes (HLA-A, -B, -C, -E, -F, and -G) have functional orthologues in the MHC of the common chimpanzee (Pan troglodytes). In contrast, a nonclassical MHC class I gene discovered in the chimpanzee is not present in humans or the other African ape species. In exons and more so in introns, this Patr-AL gene is similar to the expressed A locus in the orangutan, Popy-A, suggesting they are orthologous. Patr-AL/Popy-A last shared a common ancestor with the classical MHC-A locus >20 million years ago. Population analysis revealed little Patr-AL polymorphism: just three allotypes differing only at residues 52 and 91. Patr-AL is expressed in PBMC and B cell lines, but at low level compared with classical MHC class I. The Patr-AL polypeptide is unusually basic, but its glycosylation, association with beta(2)-microglobulin, and antigenicity at the cell surface are like other MHC class I. No Patr-AL-mediated inhibition of polyclonal chimpanzee NK cells was detected. The Patr-AL gene is present in 50% of chimpanzee MHC haplotypes, correlating with presence of a 9.8-kb band in Southern blots. The flanking regions of Patr-AL contain repetitive/retroviral elements not flanking other class I genes. In sequenced HLA class I haplotypes, a similar element is present in the A*2901 haplotype but not the A*0201 or A*0301 haplotypes. This element, 6 kb downstream of A*2901, appears to be the relic of a human gene related to Patr-AL. Patr-AL has characteristics of a class I molecule of innate immunity with potential to provide common chimpanzees with responses unavailable to humans.
authors.affiliation: Department of Integrative Biology, University of California, Berkeley, CA 94720, USA. eadams@cmgm.stanford.edu
authors.forename: E J
authors.initials: EJ
authors.lastname: Adams
authors.forename: S
authors.initials: S
authors.lastname: Cooper
authors.forename: P
authors.initials: P
authors.lastname: Parham
mesh_terms: D017398:Alternative Splicing; D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D019143:Evolution, Molecular; D006071:Gorilla gorilla; D006239:Haplotypes; D015395:Histocompatibility Antigens Class I / Q000235:genetics* / Q000502:physiology; D006801:Humans; D007694:Killer Cells, Natural / Q000276:immunology; D008957:Models, Genetic; D008969:Molecular Sequence Data; D002679:Pan troglodytes / Q000276:immunology*; D010802:Phylogeny; D011110:Polymorphism, Genetic; D012333:RNA, Messenger / Q000378:metabolism; D012091:Repetitive Sequences, Nucleic Acid; D012689:Sequence Homology, Nucleic Acid
chemical_list: D015395:Histocompatibility Antigens Class I; D012333:RNA, Messenger