Arabidopsis MBP1 Gene Encodes a Conserved Ubiquitin Recognition Component of the 26S Proteasome

Multiubiquitin chain attachment is a key step leading to the selective degradation of abnormal polypeptides and many important regulatory proteins by the eukaryotic 26S proteasome. However, the mechanism by which the 26S complex recognizes this posttranslational modification is unknown. Using synthe...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 1996-01, Vol.93 (2), p.856-860
Main Authors: Van Nocker, Steven, Deveraux, Quinn, Rechsteiner, Martin, Vierstra, Richard D.
Format: Article
Language:English
Subjects:
Amino Acid Sequence
Amino acids
Arabidopsis
Arabidopsis - genetics
Arabidopsis Proteins
Base Sequence
Carrier Proteins - genetics
Carrier Proteins - metabolism
Cellulose nitrate
Cloning, Molecular
Complementary DNA
Cysteine Endopeptidases - genetics
Cysteine Endopeptidases - metabolism
DNA
Gels
Genes, Plant
Genetics
Humans
Libraries
Molecular Probe Techniques
Molecular Sequence Data
Multienzyme Complexes - genetics
Multienzyme Complexes - metabolism
Open reading frames
Peptides
Proteasome Endopeptidase Complex
Proteins
Recombinant Proteins
Sequence Analysis, DNA
Sequence Homology, Amino Acid
Species Specificity
Ubiquitins
Ubiquitins - metabolism
Yeasts
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Summary:Multiubiquitin chain attachment is a key step leading to the selective degradation of abnormal polypeptides and many important regulatory proteins by the eukaryotic 26S proteasome. However, the mechanism by which the 26S complex recognizes this posttranslational modification is unknown. Using synthetic multiubiquitin chains to probe an expression library for interacting proteins, we have isolated an Arabidopsis cDNA, designated MBP1, that encodes a 41-kDa acidic protein exhibiting high affinity for chains, especially those containing four or more ubiquitins. Based on similar physical and immunological properties, multiubiquitin binding affinities, and peptide sequence, MBP1 is homologous to subunit 5a of the human 26S proteasome. Structurally related proteins also exist in yeast, Caenorhabditis, and other plant species. Given their binding properties, association with the 26S proteasome, and widespread distribution, MBP1, S5a, and related proteins likely function as essential ubiquitin recognition components of the 26S proteasome.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.93.2.856