title: Molecular characterization and  tissue-specific expression of invariant chain in the muscovy duck (Cairina  moschata).
abstract: The  invariant chain (Ii) plays an important role as a chaperone for MHC II  maturation and facilitates antigen presentation in vertebrates. We cloned, characterized  and made a homology analysis of healthy adult muscovy duck Ii (MDIi), from a  poultry farm in the suburban district of Hefei city in China, by rapid  amplification of cDNA ends (RACE)-PCR and by measuring expression of the MDIi gene in various tissues by real-time quantitative PCR. A full-length cDNA  sequence of MDIi was obtained, 1188-bp long, encoding a 222-amino acid  protein. A comparison of the amino acid sequence of Ii between muscovy duck and  other birds showed high similarity (66.3-95.3%). Characteristic functional  domains found in Ii of other species, such as cytoplasmic domain, transmembrane  domain, class II-associated  Ii-derived peptide (CLIP) and trimerization domain, were identified in MDIi.  Although all functional domains of Ii were found to be highly conserved, small  differences in the CLIP sequence occur among the various species. Expression of MDIi was detected in all tissues at different levels. A higher  expression level was found in the spleen, intestinal mucosa and the bursa stipe  (bursa of Fabricius stipe) than other tissues. This tissue-specific expression  suggests that MDIi plays an essential role in all tissues and differential  expression may be a function of the innate structures and essential functions  of these tissues.
authors.affiliation: Key Laboratory of Zoonoses of Anhui Province, Anhui Agricultural University, Hefei, China.
authors.forename: S J
authors.initials: SJ
authors.lastname: Liu
authors.forename: F F
authors.initials: FF
authors.lastname: Chen
authors.forename: Y
authors.initials: Y
authors.lastname: Dai
authors.forename: C
authors.initials: C
authors.lastname: Wu
authors.forename: Q S
authors.initials: QS
authors.lastname: Ni
authors.forename: W Y
authors.initials: WY
authors.lastname: Yu
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D015703:Antigens, CD / Q000235:genetics / Q000276:immunology; D000944:Antigens, Differentiation, B-Lymphocyte / Q000235:genetics* / Q000276:immunology; D030161:Avian Proteins / Q000235:genetics / Q000276:immunology; D003001:Cloning, Molecular; D017124:Conserved Sequence; D018076:DNA, Complementary / Q000096:biosynthesis; D004372:Ducks / Q000235:genetics* / Q000276:immunology / Q000378:metabolism; D000949:Histocompatibility Antigens Class II / Q000235:genetics* / Q000276:immunology; D007113:Immunity, Innate / Q000235:genetics*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009928:Organ Specificity; D010802:Phylogeny; D016133:Polymerase Chain Reaction / Q000379:methods; D017434:Protein Structure, Tertiary; D012333:RNA, Messenger / Q000032:analysis / Q000096:biosynthesis; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid
chemical_list: D015703:Antigens, CD; D000944:Antigens, Differentiation, B-Lymphocyte; D030161:Avian Proteins; D018076:DNA, Complementary; D000949:Histocompatibility Antigens Class II; D012333:RNA, Messenger; C045084:invariant chain