title: The intracellular transport of MHC class II molecules in the absence of HLA-DM.
abstract: The HLA-DM alpha and HLA-DM beta genes encode a nonpolymorphic, class II-like molecule that functions by an as yet undefined mechanism in the assembly of processed antigen-HLA class II complexes. Mutant cells that fail to express HLA-DM are deficient in Ag processing. We previously isolated a subcellular compartment in mouse B cells in which functional processed Ag-class II complexes are first formed, referred to as the peptide-loading compartment. Here, evidence is provided that HLA-DM resides in a subcellular compartment with the characteristics of a peptide-loading compartment in a human B lymphoblastoid cell line, but is not required for the intracellular transport of HLA-DR3 molecules to a corresponding compartment in HLA-DM-deficient cells. Thus, the primary defect in HLA-DM-deficient cells does not appear to be a failure in the intracellular trafficking of class II molecules.
authors.affiliation: Department of Biochemistry, Molecular Biology, and Cell Biology, Northwestern University, Evanston, IL 60208, USA.
authors.forename: J M
authors.initials: JM
authors.lastname: Green
authors.forename: R
authors.initials: R
authors.lastname: DeMars
authors.forename: X
authors.initials: X
authors.lastname: Xu
authors.forename: S K
authors.initials: SK
authors.lastname: Pierce
mesh_terms: D000944:Antigens, Differentiation, B-Lymphocyte / Q000096:biosynthesis / Q000276:immunology / Q000378:metabolism; D001402:B-Lymphocytes / Q000378:metabolism*; D001692:Biological Transport / Q000276:immunology; D002460:Cell Line; D006681:HLA-D Antigens / Q000096:biosynthesis / Q000378:metabolism*; D015803:HLA-DR3 Antigen / Q000096:biosynthesis / Q000502:physiology; D000949:Histocompatibility Antigens Class II / Q000096:biosynthesis / Q000276:immunology / Q000378:metabolism; D006801:Humans; D007976:Leupeptins / Q000494:pharmacology; D008213:Lymphocyte Activation; D011480:Protease Inhibitors / Q000494:pharmacology; D013347:Subcellular Fractions / Q000276:immunology
chemical_list: D000944:Antigens, Differentiation, B-Lymphocyte; C416189:H2-M antigens; D006681:HLA-D Antigens; C084245:HLA-DM antigens; D015803:HLA-DR3 Antigen; D000949:Histocompatibility Antigens Class II; D007976:Leupeptins; D011480:Protease Inhibitors; C045084:invariant chain; C032854:leupeptin