The ubiquitin-related BAG-1 provides a link between the molecular chaperones Hsc70/Hsp70 and the proteasome.
The BAG-1 protein modulates the chaperone activity of Hsc70 and Hsp70 in the mammalian cytosol and nucleus. Remarkably, BAG-1 possesses a ubiquitin-like domain at its amino terminus, suggesting a link to the ubiquitin/proteasome system. Here we show that BAG-1 is indeed associated with the 26 S proteasome in HeLa cells. ... Binding of the chaperone cofactor to the proteolytic complex is regulated by ATP hydrolysis and is not mediated by Hsc70 and Hsp70. The presented findings reveal a role of BAG-1 as a physical link between the Hsc70/Hsp70 chaperone system and the proteasome. In fact, targeting of BAG-1 to the proteasome promotes an association of the chaperones with the proteolytic complex in vitro and in vivo. A regulatory function of the chaperone cofactor at the interface between protein folding and protein degradation is thus indicated.
Mesh Terms:
Amino Acid Sequence, Carrier Proteins, Cysteine Endopeptidases, DNA-Binding Proteins, HSC70 Heat-Shock Proteins, HSP70 Heat-Shock Proteins, Hela Cells, Humans, Molecular Sequence Data, Multienzyme Complexes, Proteasome Endopeptidase Complex, Protein Binding, Protein Isoforms, Transcription Factors, Ubiquitins
Amino Acid Sequence, Carrier Proteins, Cysteine Endopeptidases, DNA-Binding Proteins, HSC70 Heat-Shock Proteins, HSP70 Heat-Shock Proteins, Hela Cells, Humans, Molecular Sequence Data, Multienzyme Complexes, Proteasome Endopeptidase Complex, Protein Binding, Protein Isoforms, Transcription Factors, Ubiquitins
J. Biol. Chem.
Date: Feb. 18, 2000
PubMed ID: 10671488
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