Defective intracellular transport as a common mechanism limiting expression of inappropriately paired class II major histocompatibility complex alpha/beta chains
| Autor: | L R Hendrix, John E. Coligan, Ronald N. Germain, Andrea J. Sant, W L Maloy |
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| Rok vydání: | 1991 |
| Předmět: |
Macromolecular Substances
Genes MHC Class II Molecular Sequence Data Immunology Golgi Apparatus Alpha (ethology) Transfection Major histocompatibility complex Cell membrane Mice Endoglycosidase H L Cells Leucine medicine Animals Immunology and Allergy Amino Acid Sequence Beta (finance) Alleles biology Endoplasmic reticulum Cell Membrane Histocompatibility Antigens Class II Antibodies Monoclonal Articles Isotype medicine.anatomical_structure Gene Expression Regulation Biochemistry biology.protein Biophysics Peptides Protein Processing Post-Translational Intracellular |
| Zdroj: | The Journal of Experimental Medicine |
| ISSN: | 1540-9538 0022-1007 |
| DOI: | 10.1084/jem.174.4.799 |
| Popis: | Distinct combinations of class II major histocompatibility complex (MHC) alpha and beta chains show widely varying efficiencies of cell surface expression in transfected cells. Previous studies have analyzed the regions of the class II chains that are critically involved in this phenomenon of variable expression and have shown a predominant effect of the NH2-terminal domains comprising the peptide-binding site. The present experiments attempt to identify the post-translational defects responsible for this variation in surface class II molecule expression for both interisotypic alpha/beta combinations failing to give rise to any detectable cell membrane molecules (e.g., E alpha A beta k) and intraisotypic pairs with inefficient surface expression (e.g., A alpha d A beta k). The results of metabolic labeling and immunoprecipitation experiments using L cell transfectants demonstrate that in both of these cases, the alpha and beta chains form substantial amounts of stable intracellular dimers. However, the isotype- and allele-mismatched combinations do not show the typical post-translational increases in molecular weight that accompany maturation of the N-linked glycans of class II MHC molecules. Studies with endoglycosidase H reveal that no or little progression to endoglycosidase H resistance occurs for these mismatched dimers. These data are consistent with active or passive retention of relatively stable and long-lived mismatched dimers in a pre-medial-Golgi compartment, possibly in the endoplasmic reticulum itself. This retention accounts for the absent or poor surface expression of these alpha/beta combinations, and suggests that conformational effects of the mismatching in the NH2-terminal domain results in a failure of class II molecules to undergo efficient intracellular transport. |
| Databáze: | OpenAIRE |
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