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Ubiquitin-mediated proteolysis of a short lived regulatory protein depends on its cellular localization

Item Type:Article
Title:Ubiquitin-mediated proteolysis of a short lived regulatory protein depends on its cellular localization
Creators Name:Lenk, U. and Sommer, T.
Abstract:In this study we demonstrate that the Deg1 degradation signal of the transcriptional repressor Matα2 confers compartment-specific turnover to a reporter protein. Rapid degradation of a Deg1-containing fusion protein is observed only when the reporter is efficiently imported into the nucleus. In contrast, a reporter that is constantly exported from the nucleus exhibits an extended half-life. Furthermore, nuclear import functions are crucial for both Deg1-induced degradation as well as for the turnover of the endogenous Matα2 protein. The conjugation of ubiquitin to a Deg1-containing reporter protein is abrogated in mutants affected in nuclear import. Obviously, the Deg1 signal initiates rapid proteolysis within the nucleoplasm, whereas in the cytosol it mediates turnover via a slower pathway. In both pathways the ubiquitin-conjugating enzymes Ubc6p/Ubc7p play a pivotal role. These observations imply that both the cellular targeting of a substrate and the compartment-specific activity of components of the ubiquitin-proteasome system define the half-life of naturally short-lived proteins.
Keywords:Carrier Proteins, Cell Nucleus, Cytoplasm, Escherichia Coli, Fluorescence Microscopy, Fungal Proteins, Genetic Transcription, Green Fluorescent Proteins, Homeodomain Proteins, Kinetics, Ligases, Luminescent Proteins, Membrane Proteins, Mutation, Plasmids, Precipitin Tests, Protein Transport, Recombinant Fusion Proteins, Reporter Genes, Repressor Proteins, Saccharomyces Cerevisiae, Saccharomyces Cerevisiae Proteins, Time Factors, Ubiquitin-Conjugating Enzymes, Ubiquitins
Source:Journal of Biological Chemistry
Publisher:American Society for Biochemistry and Molecular Biology
Page Range:39403-39410
Date:1 January 2000
Official Publication:https://doi.org/10.1074/jbc.M006949200
PubMed:View item in PubMed

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