title: Expression, purification and assembly of soluble multimeric MHC class II-invariant chain complexes.
abstract: Major histocompatibility class (MHC) II molecules are essential for running adaptive immune response. They are produced in the ER and targeted to late endosomes with the help of invariant chain (Ii) trimers. Ii trimerization may be induced by the Ii TM domain. To enable mechanistic and structural studies of MHC class II-Ii assembly, soluble forms of the complexes were expressed. We show that Ii trimerizes in the absence of the transmembrane part, prior to binding of α/β chains. The biochemical analysis supports the suggestion that the MHC class II-Ii complexes are not necessarily trimers of trimers, but that the Ii trimer can also be occupied by one or two MHC class II complexes.
authors.affiliation: Department of Biochemistry, Molecular and Structural Biology and Centre for Protein and Structure Production, Jozef Stefan Institute, Ljubljana, Slovenia.
authors.forename: Dušana
authors.initials: D
authors.lastname: Majera
authors.forename: Katarina Črnigoj
authors.initials: KČ
authors.lastname: Kristan
authors.forename: Jacques
authors.initials: J
authors.lastname: Neefjes
authors.forename: Dušan
authors.initials: D
authors.lastname: Turk
authors.forename: Marko
authors.initials: M
authors.lastname: Mihelič
mesh_terms: D002462:Cell Membrane / Q000378:metabolism; D015870:Gene Expression; D057809:HEK293 Cells; D006681:HLA-D Antigens / Q000737:chemistry* / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D006801:Humans; D055503:Protein Multimerization; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D012995:Solubility
chemical_list: D006681:HLA-D Antigens