Interaction of Murine BiP/GRP78 with the DnaJ Homologue MTJ1*
| Autor: | Mathieu Chevalier, Hong Rhee, Ebrahim C. Elguindi, Sylvie Y. Blond |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2000 |
| Předmět: |
endocrine system
Protein family genetic structures Mutant Amino Acid Motifs Molecular Sequence Data Plasma protein binding macromolecular substances Biology Biochemistry Models Biological Article Mice Heat shock protein Microsomes Animals HSP70 Heat-Shock Proteins Amino Acid Sequence Molecular Biology Peptide sequence Endoplasmic Reticulum Chaperone BiP Heat-Shock Proteins Adenosine Triphosphatases Cell Nucleus Dose-Response Relationship Drug Endoplasmic reticulum Circular Dichroism Escherichia coli Proteins Cell Biology HSP40 Heat-Shock Proteins Transmembrane protein Recombinant Proteins Neoplasm Proteins Enzyme Activation Kinetics Membrane protein Mutagenesis Site-Directed Carrier Proteins Peptides Molecular Chaperones Plasmids Protein Binding |
| Popis: | The activity of Hsp70 proteins is regulated by accessory proteins, among which the most studied are the members of the DnaJ-like protein family. BiP/GRP78 chaperones the translocation and maturation of secreted and membrane proteins in the endoplasmic reticulum. No DnaJ-like partner has been described so far to regulate the function of mammalian BiP/GRP78. We show here that murine BiP/GRP78 interacts with the lumenal J domain of the murine transmembrane protein MTJ1 (J-MTJ1). J-MTJ1 stimulates the ATPase activity of BiP/GRP78 at stoichiometric concentrations. The C-terminal tail of BiP/GRP78 is not required for the interaction with J-MTJ1, leaving the function of this portion of the molecule still unclear. Physical interactions between J-MTJ1 and BiP/GRP78 are stable and can be abolished by a single histidine --glutamine substitution in the highly conserved HPD motif shared by all DnaJ-like proteins. The J-MTJ1 fragment, but not the mutant J-MTJ1:H89Q fragment, stimulates the ATPase activity of Escherichia coli DnaK, although at a higher concentration than its genuine partner DnaJ. Full-length DnaJ does not stimulate BiP over the range of concentrations investigated. These results indicate that the J domain of MTJ1 is sufficient for its interaction with BiP/GRP78 and cannot be substituted by E. coli DnaJ. |
| Databáze: | OpenAIRE |
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