Thioredoxin Txnl1/TRP32 is a redox-active cofactor of the 26 S proteasome.
The 26 S proteasome is a large proteolytic machine, which degrades most intracellular proteins. We found that thioredoxin, Txnl1/TRP32, binds to Rpn11, a subunit of the regulatory complex of the human 26 S proteasome. Txnl1 is abundant, metabolically stable, and widely expressed and is present in the cytoplasm and nucleus. ... Txnl1 has thioredoxin activity with a redox potential of about -250 mV. Mutant Txnl1 with one active site cysteine replaced by serine formed disulfide bonds to eEF1A1, a substrate-recruiting factor of the 26 S proteasome. eEF1A1 is therefore a likely physiological substrate. In response to knockdown of Txnl1, ubiquitin-protein conjugates were moderately stabilized. Hence, Txnl1 is the first example of a direct connection between protein reduction and proteolysis, two major intracellular protein quality control mechanisms.
Mesh Terms:
Amino Acid Sequence, Cell Line, Cell Nucleus, Gene Knockdown Techniques, Humans, Molecular Sequence Data, Oxidation-Reduction, Peptide Elongation Factor 1, Proteasome Endopeptidase Complex, Protein Binding, Protein Stability, Solubility, Substrate Specificity, Thioredoxins
Amino Acid Sequence, Cell Line, Cell Nucleus, Gene Knockdown Techniques, Humans, Molecular Sequence Data, Oxidation-Reduction, Peptide Elongation Factor 1, Proteasome Endopeptidase Complex, Protein Binding, Protein Stability, Solubility, Substrate Specificity, Thioredoxins
J. Biol. Chem.
Date: May. 29, 2009
PubMed ID: 19349277
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