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Research article - Peer-reviewed, 2013

Pitfalls in invertebrate proteasome assays

Goetze, Sandra; Bose, Aneesh; Abele, Doris; Sokolova, Inna M.; Saborowski, Reinhard


The ubiquitin-proteasome system controls a variety of essential intracellular processes through directed protein turnover. The invertebrate proteasome has recently gained increasing interest with respect to central physiological processes and pathways in different taxa. A pitfall in proteasome activity assays, represented by the trypsin-like, chymotrypsin-like or caspase-like site, lies in the fact that most commonly used experimental substrates are susceptible to degradation by non-proteasomal proteolytic enzymes, which can lead to erroneous interpretation of activity data obtained. Through the use of a proteasome-specific inhibitor, epoxomicin, we showed that the shares of proteasomal and non-proteasomal activities in the degradation of a model polypeptide substrate for chymotrypsin-like activity vary considerably between invertebrate taxa. Crustacean muscle tissue and hemocytes showed almost exclusively proteasomal activity. In yeast, approximately 90% of total proteolytic activity can be attributed to the proteasome. In contrast, proteasomal activity comprises only 20-60% of the total proteolytic activity in bivalve tissues. These results reveal that, without verification of the shares of proteasomal and non-proteasomal activities in crude extracts through the use of highly specific inhibitors, common proteasomal enzyme assays should be used and interpreted with caution.


proteasome; bivalve; Crustacea; epoxomicin; protein catabolism

Published in

Journal of Experimental Biology
2013, volume: 216, number: 8, pages: 1351-1354

Authors' information

Goetze, Sandra
Helmholtz Association
Goetze, Sandra
University of North Carolina
Alfred Wegener Institute
Abele, Doris
Helmholtz Association
Sokolova, Inna M.
University of North Carolina
Saborowski, Reinhard
Helmholtz Association

UKÄ Subject classification

Biochemistry and Molecular Biology

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