ABSTRACT
Objective:To investigate the intracellular localization and association of chicken major histocompatibility complex class Ⅰsubunits with invariant chain.Methods:At first,the sequences of MHCⅠ ? and ?2m subunits were amplified with RT-PCR.Secondly,we constructed the eukaryotic expression plasmids of MHCⅠ ? and MHCⅠ?2m that was fused with red or enhanced green fluorescent protein,respectively.The recombinant plasmids of MHC Ⅰsubunits and pEGFP-C1-Ii that could express enhanced green fluorescent protein were transiently transfected into COS-7 cells with Lipofectamine 2000.Immunofluorescence microscopy was carried out to detect the expression and intracellular localization of Ii and MHC Ⅰsubunits,and immunoprecipitation was used for analyzing their association.Results:The colocalization was found in endocytic compartments when GFP-Ii,MHCⅠ?-RFP and MHCⅠ?2m-RFP were co-expressed in COS-7 cells.Immunoprecipitation of Ii showed that GFP-Ii co-isolated with MHCⅠ?-GFP and MHCⅠ?2m-GFP subunits when COS-7 cells were transiently transfected with pEGFP-C1-Ii,pEGFP-N1-MHCⅠ? and pEGFP-N1-MHCⅠ?2m.Conclusion:Chicken Ii can not effectively associate with single ? or ?2m subunits from chicken MHC Ⅰmolecules,but Ii and the integrated MHC Ⅰmolecule can form the complexes that are colocalized in endomembrane system of COS-7 cells.