Document Detail

Proteasome subunit zeta, a putative ribonuclease, is also found as a free monomer.
MedLine Citation:
PMID:  10363657     Owner:  NLM     Status:  MEDLINE    
20 S Proteasomes are large proteinase complexes found in eukaryotic cells where they degrade cell proteins in an ATP-dependent manner. Proteasomes consist of 14 different subunits. One of them, zeta, was found in HeLa cells at a concentration of 890 microg per g of cell protein. A large proportion of zeta was found in the free state rather than incorporated into proteasomes, namely 28% in HeLa cells and 37% in BSC-1 cells. Free zeta was found in both nuclei and cytoplasm. In HeLa cells free zeta had a t1/2 of 2.8 h, compared to 5 d for proteasomes, and did not exchange with zeta in proteasomes. We confirmed (Petit F et al.: Biochem. J. 326: 93-98 (1997)) that both 20 S proteasomes and free zeta subunits possess RNase activity though the activities were very low: 4 mMoles and 0.6 mMoles of tobacco mosaic virus RNA degraded per mole of enzyme per min, respectively. The physiological function of the relatively abundant zeta monomers is not known.
L Jørgensen; K B Hendil
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Molecular biology reports     Volume:  26     ISSN:  0301-4851     ISO Abbreviation:  Mol. Biol. Rep.     Publication Date:  1999 Apr 
Date Detail:
Created Date:  1999-09-14     Completed Date:  1999-09-14     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0403234     Medline TA:  Mol Biol Rep     Country:  NETHERLANDS    
Other Details:
Languages:  eng     Pagination:  119-23     Citation Subset:  IM    
August Krogh Institute, Copenhagen O, Denmark.
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MeSH Terms
Cysteine Endopeptidases / chemistry*,  isolation & purification,  metabolism
Electrophoresis, Polyacrylamide Gel
Erythrocytes / enzymology
Hela Cells
Multienzyme Complexes / chemistry*,  isolation & purification,  metabolism
Proteasome Endopeptidase Complex
Ribonucleases / metabolism*
Reg. No./Substance:
0/Multienzyme Complexes; EC 3.1.-/Ribonucleases; EC 3.4.22.-/Cysteine Endopeptidases; EC Endopeptidase Complex
Erratum In:
Mol Biol Rep 1999 Aug;26(3):215-6

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