title: Molecular cloning and mRNA expression of duck invariant chain.
abstract: In the present study we identified a duck invariant chain (Ii) cDNA, named duck Ii-1, by RT-PCR and RACE. It was 1190 bp in length and contained a 669 bp open reading frame. An alternative transcript encoding a thyroglobulin (Tg)-containing form of Ii, named duck Ii-2, was also found in duck. The putative amino acid sequence of duck Ii-1 showed an 82% similarity to chicken Ii-1 and about 60% similarity to its mammalian homologues. The similarity of the Tg domain between duck and chicken Ii-2 was 96%, and about 70% between duck and mammalian Ii. The result of RT-PCR showed that Ii mRNA was extensively expressed in various tissues. High levels of both Ii-1 and Ii-2 mRNA were observed in the spleen and bursa of Fabricius. The predicted three-dimensional (3D) structures of duck Ii trimerization and Tg domain are similar to the corresponding regions of human Ii analyzed by comparative protein modeling. These findings indicate that the two isoforms of duck Ii, which strongly expressed in the major immune organs, share structural identity with human Ii.
authors.affiliation: Department of Molecular and Cell Biology, School of Life Science, University of Science and Technology of China, Hefei, Anhui 230027, PR China.
authors.forename: Dalian
authors.initials: D
authors.lastname: Zhong
authors.forename: Weiyi
authors.initials: W
authors.lastname: Yu
authors.forename: Min
authors.initials: M
authors.lastname: Bao
authors.forename: Zhiben
authors.initials: Z
authors.lastname: Xu
authors.forename: Lin
authors.initials: L
authors.lastname: Li
authors.forename: Jing
authors.initials: J
authors.lastname: Liu
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000944:Antigens, Differentiation, B-Lymphocyte / Q000737:chemistry / Q000235:genetics*; D001483:Base Sequence; D002645:Chickens; D003001:Cloning, Molecular; D004372:Ducks / Q000235:genetics* / Q000276:immunology; D005786:Gene Expression Regulation; D000949:Histocompatibility Antigens Class II / Q000737:chemistry / Q000235:genetics*; D008969:Molecular Sequence Data; D011487:Protein Conformation; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism
chemical_list: D000944:Antigens, Differentiation, B-Lymphocyte; D000949:Histocompatibility Antigens Class II; D012333:RNA, Messenger; C045084:invariant chain