title: [Effect of the targeted mutation of sorting motifs on the localization of porcine Ia-associated invariant chain].
abstract: OBJECTIVE
  To investigate the effect of amino acids around two Leu-based motifs (Leu 7/Ile 8 and Met 16/Leu 17) in the cytosolic tail of porcine Ia-associated invariant chain (Ii) on endomembrane system positioning function.
  
  
  METHODS
  At first, two Leu-based motifs and amino acids around motifs were mutated through site-directed mutagenesis of the megaprimer PCR method, and the mutant genes were ligated to the vector pEGFP-C1, respectively. Twenty-one mutations of Ii recombinant plasmid were obtained and transiently transfected into the COS-7 cells by Lipofectamine(TM) 2000. Fluorescence microscopy was used to detect the intracellular localization of mutation Ii.
  
  
  RESULTS
  Leu 7/Ile 8 and Met 16/Leu 17 independently mediated the intracellular localization of mutation Ii. When one leucine motif was kept and the amino acid around the other leucine motif was mutated, fusion protein GFP-Ii was located in the endomembrane system or distributed in the whole cell.
  
  
  CONCLUSIONS
  pig Ii comprises two independent sorting signals, and the functional Leu-based sorting signal requires specific neighboring residues.
authors.affiliation: Laboratory Animal Center, Anhui Medical University, Hefei 230032, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Liu
authors.affiliation: Anhui Agriculture University, Hefei 230036, China.
authors.forename: Fazhi
authors.initials: F
authors.lastname: Xu
mesh_terms: D020816:Amino Acid Motifs / Q000235:genetics*; D000595:Amino Acid Sequence; D000818:Animals; D000944:Antigens, Differentiation, B-Lymphocyte / Q000235:genetics* / Q000378:metabolism; D019556:COS Cells; D002522:Chlorocebus aethiops; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D000949:Histocompatibility Antigens Class II / Q000235:genetics* / Q000378:metabolism; D042541:Intracellular Space / Q000378:metabolism; D007532:Isoleucine / Q000235:genetics / Q000378:metabolism; D007930:Leucine / Q000235:genetics / Q000378:metabolism; D008715:Methionine / Q000235:genetics / Q000378:metabolism; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D021381:Protein Transport / Q000235:genetics; D013552:Swine
chemical_list: D000944:Antigens, Differentiation, B-Lymphocyte; D000949:Histocompatibility Antigens Class II; C045084:invariant chain; D007532:Isoleucine; D049452:Green Fluorescent Proteins; D008715:Methionine; D007930:Leucine