Characterization of a lysozyme-major histocompatibility complex class II molecule-loading compartment as a specialized recycling endosome in murine B lymphocytes.
We have previously identified an intracellular compartment involved in the association between processed lysozyme and IAk major histocompatibility complex class II molecules (called the lysozyme-loading compartment (LLC)). Here, we show that the LLC polypeptide composition analyzed by two-dimensional gel electrophoresis shares similarities with that of early endosomes, but not with that of late endosomes. The transferrin receptor, a well known marker for both early and recycling endosomes, colocalizes with IAk molecules in LLC. Moreover, both transferrin and fluid-phase markers have access to LLC after 15 min of internalization. In the presence of concanamycin B, SDS-stable dimer formation and transport of class II molecules out of LLC are impaired. In contrast, nocodazole treatment has no effect. These results suggest that LLC is a specialized compartment of the recycling pathway involved in lysozyme loading and in the targeting of lysozyme-major histocompatibility class II complexes toward the cell surface.
Centre d'Immunologie, INSERM-CNRS de Marseille-Luminy, Case 906, 13288 Marseille Cedex 09, France. gorvel@ciml.univ-mrs.fr
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Escola
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Deleuil
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Stang
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Boretto
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Chavrier
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Gorvel
D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001402:B-Lymphocytes / Q000201:enzymology / Q000276:immunology* / Q000648:ultrastructure; D002458:Cell Fractionation; D019281:Dimerization; D015180:Electrophoresis, Gel, Two-Dimensional; D004705:Endocytosis; D011992:Endosomes / Q000201:enzymology / Q000276:immunology* / Q000648:ultrastructure; D000949:Histocompatibility Antigens Class II / Q000187:drug effects / Q000302:isolation & purification / Q000378:metabolism*; D006735:Horseradish Peroxidase / Q000378:metabolism; D007700:Kinetics; D016393:Lymphoma, B-Cell; D018942:Macrolides; D051379:Mice; D008854:Microscopy, Electron; D009113:Muramidase / Q000302:isolation & purification / Q000378:metabolism*; D015739:Nocodazole / Q000494:pharmacology; D014407:Tumor Cells, Cultured
D000900:Anti-Bacterial Agents; D000949:Histocompatibility Antigens Class II; D018942:Macrolides; C036979:concanamycin B; D006735:Horseradish Peroxidase; D009113:Muramidase; D015739:Nocodazole