Assembled pre-B cell receptor complexes are retained in the endoplasmic reticulum by a mechanism that is not selective for the pseudo-light chain
| Autor: | Jacques Neefjes, Evert de Vries, Jannie Borst, Gaby S. Brouns |
|---|---|
| Rok vydání: | 1996 |
| Předmět: |
Receptor complex
Endoplasmic reticulum B-cell receptor Receptors Antigen B-Cell ER retention STIM1 Biological Transport Cell Biology Biology Protein-Tyrosine Kinases Endoplasmic Reticulum Biochemistry Cell biology Kinetics Cell surface receptor hemic and lymphatic diseases Tumor Cells Cultured Humans Immunoglobulin Light Chains Kinase activity Signal transduction Protein Precursors Molecular Biology Signal Transduction |
| Zdroj: | The Journal of biological chemistry. 271(32) |
| ISSN: | 0021-9258 |
| Popis: | The pre-B cell receptor (BCR) complex, consisting of micro heavy chain, a pseudo-light chain, and the Mb-1/B29 heterodimer, directs the transition to the mature B cell stage. Plasma membrane expression of the pre-BCR is extremely low, despite its presumed signaling function. We have compared assembly and intracellular transport of the pre-BCR complex with that of the BCR complex in mature B cells. Synthesis and assembly rate of pre-BCR and BCR components are comparable. However, the pre-BCR is subject to a highly efficient retention mechanism, which only allows exit of a few percent of the complexes from the endoplasmic reticulum (ER). This small transported pool of pre-BCR complexes is significantly enriched for protein-tyrosine kinase activity, as compared with the ER-localized receptor pool. Accordingly, the Src-related tyrosine kinase Lyn was found in the transported glycoprotein fraction but not in association with ER-localized glycoproteins. Upon introduction of a conventional light chain into pre-B cells, plasma membrane receptor levels increased, but the efficiency of intracellular transport of the receptor complex was not restored to that in mature B cells. This indicates that the ER retention mechanism is not selective for the pseudo-light chain and may be inherent to pre-B cells. We propose that this retention mechanism contributes to the regulation of pre-BCR-mediated signal transduction. |
| Databáze: | OpenAIRE |
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