부산대학교 도서관

The 26 S proteasome is a large proteolytic machine, which degrades most intracenular 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, metabofically 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 Txn;l1 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 Txnll, 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. [ABSTRACT FROM AUTHOR]