title: Lipid raft-independent B cell receptor-mediated antigen internalization and intracellular trafficking.
abstract: The Ag-specific B cell receptor (BCR) expressed by B lymphocytes has two distinct functions upon interaction with cognate Ag: signal transduction (generation of intracellular second messenger molecules) and Ag internalization for subsequent processing and presentation. While it is known that plasma membrane domains, termed lipid rafts, are involved in BCR-mediated signal transduction, the precise role of plasma membrane lipid rafts in BCR-mediated Ag internalization and intracellular trafficking is presently unclear. Using a highly characterized model system, it was determined that while plasma membrane lipid rafts can be internalized by B lymphocytes, lipid rafts do not represent a major pathway for the rapid and efficient internalization of cell surface Ag-BCR complexes. Moreover, internalized plasma membrane lipid rafts are delivered to intracellular compartments distinct from those to which the bulk of internalized Ag-BCR complexes are delivered. These results demonstrate that B lymphocytes, like other cell types, possess at least two distinct endocytic pathways (i.e., clathrin-coated pits and plasma membrane lipid rafts) that deliver internalized ligands to distinct intracellular compartments. Furthermore, Ag-BCR complexes differentially access these two distinct internalization pathways.
authors.affiliation: Center for Immunology and Microbial Disease, Albany Medical College, NY 12208, USA.
authors.forename: Michelle A
authors.initials: MA
authors.lastname: Putnam
authors.forename: Amy E
authors.initials: AE
authors.lastname: Moquin
authors.forename: Megan
authors.initials: M
authors.lastname: Merrihew
authors.forename: Christopher
authors.initials: C
authors.lastname: Outcalt
authors.forename: Emily
authors.initials: E
authors.lastname: Sorge
authors.forename: Adriana
authors.initials: A
authors.lastname: Caballero
authors.forename: Timothy A
authors.initials: TA
authors.lastname: Gondré-Lewis
authors.forename: James R
authors.initials: JR
authors.lastname: Drake
mesh_terms: D000818:Animals; D000941:Antigens / Q000378:metabolism*; D001402:B-Lymphocytes / Q000276:immunology / Q000378:metabolism; D002772:Cholera Toxin / Q000276:immunology / Q000378:metabolism; D004705:Endocytosis / Q000276:immunology*; D006735:Horseradish Peroxidase / Q000378:metabolism; D006801:Humans; D007424:Intracellular Fluid / Q000276:immunology* / Q000378:metabolism*; D007700:Kinetics; D046911:Macromolecular Substances; D021962:Membrane Microdomains / Q000502:physiology*; D051379:Mice; D021381:Protein Transport / Q000276:immunology; D011947:Receptors, Antigen, B-Cell / Q000502:physiology*; D014162:Transfection; D014407:Tumor Cells, Cultured
chemical_list: D000941:Antigens; D046911:Macromolecular Substances; D011947:Receptors, Antigen, B-Cell; D002772:Cholera Toxin; D006735:Horseradish Peroxidase