Functional characterization of a lysosomal sorting motif in the cytoplasmic tail of HLA-DObeta
| Autor: | Thomas J. Kindt, Alexandre Brunet, Francis Deshaies, Jacques Thibodeau, Angela Samaan |
|---|---|
| Rok vydání: | 2000 |
| Předmět: |
Cytoplasm
Recombinant Fusion Proteins Endocytic cycle Molecular Sequence Data Biology Major histocompatibility complex Transfection Biochemistry Flow cytometry Structure-Activity Relationship Consensus Sequence medicine Humans Amino Acid Sequence Tyrosine Molecular Biology HLA-D Antigens Microscopy Confocal medicine.diagnostic_test Endoplasmic reticulum Cell Biology Molecular biology Transmembrane protein Cell biology Amino Acid Substitution biology.protein Mutagenesis Site-Directed Lysosomes Dimerization Intracellular HeLa Cells Signal Transduction |
| Zdroj: | The Journal of biological chemistry. 275(47) |
| ISSN: | 0021-9258 |
| Popis: | HLA-DO is an intracellular non-classical class II major histocompatibility complex molecule expressed in the endocytic pathway of B lymphocytes, which regulates the loading of antigenic peptides onto classical class II molecules such as HLA-DR. The activity of HLA-DO is mediated through its interaction with the peptide editor HLA-DM. Here, our results demonstrate that although HLA-DO is absolutely dependent on its association with DM to egress the endoplasmic reticulum, the cytoplasmic portion of its beta chain encodes a functional lysosomal sorting signal. By confocal microscopy and flow cytometry analysis, we show that reporter transmembrane molecules fused to the cytoplasmic tail of HLA-DObeta accumulated in Lamp-1(+) vesicles of transfected HeLa cells. Mutagenesis of a leucine-leucine motif abrogated lysosomal accumulation and resulted in cell surface redistribution of reporter molecules. Finally, we show that mutation of the di-leucine sequence in DObeta did not alter its lysosomal sorting when associated with DM molecules. Taken together, these results demonstrate that lysosomal expression of the DO-DM complex is mediated primarily by the tyrosine-based motif of HLA-DM and suggest that the DObeta-encoded motif is involved in the fine-tuning of the intracellular sorting. |
| Databáze: | OpenAIRE |
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