Targeting of substrates to the 26S proteasome

The ubiquitin‐proteasome pathway is the principal mechanism for the turnover of shortlived proteins in eukaryotic cells. In this pathway, the covalent ligation of ubiquitin to the substrate is a signal for recognition by the 26S proteasome. Recent studies indicate that targeting of substrates of the...

Full description

Saved in:
Bibliographic Details
Published in:The FASEB journal 1997-11, Vol.11 (13), p.1055-1066
Main Author: Pickart, Cecile M.
Format: Article
Language:English
Subjects:
Animals
Binding Sites
Macromolecular Substances
Models, Structural
ornithine decarboxylase
Ornithine Decarboxylase - metabolism
Peptide Hydrolases - chemistry
Peptide Hydrolases - metabolism
polyubiquitin chains
Proteasome Endopeptidase Complex
Protein Structure, Secondary
protein turnover
Signal Transduction
Substrate Specificity
ubiquitination
Ubiquitins - metabolism
Citations: Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:The ubiquitin‐proteasome pathway is the principal mechanism for the turnover of shortlived proteins in eukaryotic cells. In this pathway, the covalent ligation of ubiquitin to the substrate is a signal for recognition by the 26S proteasome. Recent studies indicate that targeting of substrates of the ubiquitin pathway to the proteasome is usually accomplished by the ligation of a polyubiquitin chain assembled through K48‐G76 isopeptide bonds, rather than by ligation of monoubiquitin. In addition to providing benefits in signal generation, recognition, and persistence, assigning the proteolytic targeting function to a specific specific type of polyubiquitin chain may allow monoubiquitin or polyubiquitin chains of novel structures to serve distinct targeting functions. Besides polyubiquitinated substrates, the proteasome also degrades an unknown number of proteins that are recognized without undergoing ubiquitination. Ornithine decarboxylase is the prototype ubiquitin‐independent substrate; it is targeted to the proteasome through noncovalent interaction with a specific protein factor known as antizyme. The existence of ubiquitin‐independent substrates of the proteasome raises important questions about the nature of the substrate‐ and protea‐some‐based elements that cooperate to bring about the targeting of substrates to this novel proteolytic complex.—Pickart, C. M. Targeting of substrates to the 26S proteasome. FASEB J. 11, 1055–1066 (1997)
ISSN:0892-6638
1530-6860
DOI:10.1096/fasebj.11.13.9367341