title: Endocytosis of MHC molecules by distinct membrane rafts.
abstract: In B-lymphocytes, endocytosis of MHC I and MHC II molecules is important for the cross-priming and presentation of labile antigens, respectively. Here, we report that MHC I and MHC II were internalized by separate endocytic carriers that lacked transferrin receptor. Cholera toxin B was co-internalized with MHC II, but not with MHC I, suggesting that the CLIC/GEEC pathway is involved in the uptake of MHC II. Endocytosis of MHC I and MHC II was inhibited by filipin, but only MHC II showed a strong preference for a membrane raft environment in a co-clustering analysis with G(M)1. By using a novel method for the extraction of detergent-resistant membranes (DRMs), we observed that MHC I and MHC II associate with two distinct types of DRMs. These differ in density, protein content, lipid composition, and ultrastructure. The results of cell surface biotinylation and subsequent DRM isolation show that precursors for both DRMs coexist in the plasma membrane. Moreover, clustering of MHC proteins at the cell surface resulted in shifts of the respective DRMs, revealing proximity-induced changes in the membrane environment. Our results suggest that the preference of MHC I and MHC II for distinct membrane rafts directs them to different cellular entry points.
authors.affiliation: Department of Cell Biology, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany.
authors.forename: Ruth
authors.initials: R
authors.lastname: Knorr
authors.forename: Claudia
authors.initials: C
authors.lastname: Karacsonyi
authors.forename: Robert
authors.initials: R
authors.lastname: Lindner
mesh_terms: D000818:Animals; D001402:B-Lymphocytes / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D002460:Cell Line; D018118:Chloride Channels / Q000378:metabolism; D002772:Cholera Toxin / Q000378:metabolism; D002784:Cholesterol / Q000378:metabolism; D004705:Endocytosis / Q000187:drug effects; D005372:Filipin / Q000494:pharmacology; D005677:G(M1) Ganglioside / Q000378:metabolism; D015395:Histocompatibility Antigens Class I / Q000378:metabolism*; D000949:Histocompatibility Antigens Class II / Q000378:metabolism*; D006825:Hybridomas; D007700:Kinetics; D008285:Major Histocompatibility Complex; D021962:Membrane Microdomains / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D026901:Membrane Transport Proteins / Q000187:drug effects / Q000378:metabolism*; D051379:Mice; D024101:Mitochondrial Proteins / Q000378:metabolism
chemical_list: C479423:CLIC protein, mouse; D018118:Chloride Channels; D015395:Histocompatibility Antigens Class I; D000949:Histocompatibility Antigens Class II; D026901:Membrane Transport Proteins; D024101:Mitochondrial Proteins; D005677:G(M1) Ganglioside; D005372:Filipin; D002772:Cholera Toxin; D002784:Cholesterol