title: Modo-UG, a marsupial nonclassical MHC class I locus.
abstract: Modo-UG is a class I gene located in the MHC of the marsupial Monodelphis domestica, the gray, short-tailed opossum. Modo-UG is expressed as three alternatively spliced mRNA forms, all of which encode a transmembrane form with a short cytoplasmic tail that lacks phosphorylation sites typically found in classical class I molecules. The three alternative mRNAs would encode a full-length form, an isoform lacking the alpha2 domain, and one lacking both alpha2 and alpha3 domains. Genotyping both captive-bred and wild M. domestica from different geographic regions revealed no variation in the residues that make up Modo-UG's peptide-binding groove. Modo-UG's low polymorphism is contrasting to that of a nearby class I locus, Modo-UA1, which has a highly polymorphic peptide-binding region. Absence of functional polymorphism in Modo-UG is therefore not a general feature of opossum class I genes but the result of negative selection. Modo-UG is the first MHC linked marsupial class I to be described that appears to clearly have nonclassical features.
authors.affiliation: Department of Genetics, Southwest Foundation for Biomedical Research, San Antonio, TX, 78245, USA.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Gouin
authors.forename: April M
authors.initials: AM
authors.lastname: Wright
authors.forename: Katarzyna B
authors.initials: KB
authors.lastname: Miska
authors.forename: Zuly E
authors.initials: ZE
authors.lastname: Parra
authors.forename: Paul B
authors.initials: PB
authors.lastname: Samollow
authors.forename: Michelle L
authors.initials: ML
authors.lastname: Baker
authors.forename: Robert D
authors.initials: RD
authors.lastname: Miller
mesh_terms: D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D005805:Genes, MHC Class I / Q000235:genetics*; D015395:Histocompatibility Antigens Class I / Q000145:classification / Q000235:genetics*; D008912:Minor Histocompatibility Loci / Q000235:genetics*; D008969:Molecular Sequence Data; D048309:Monodelphis / Q000235:genetics / Q000276:immunology*; D010802:Phylogeny; D011110:Polymorphism, Genetic; D012333:RNA, Messenger / Q000378:metabolism
chemical_list: D015395:Histocompatibility Antigens Class I; D012333:RNA, Messenger