Cycloheximide, a New Tool to Dissect Specific Steps in ER-Associated Degradation of Different Substrates
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C. Amshoff
Abstract
To study the degradation requirements of unassembled immunoglobulin (Ig) chains, we heterologously expressed a cDNA encoding the secretory form of murine μ in the yeast S. cerevisiae. We found that μ chains were translocated into and retained in the endoplasmic reticulum (ER) as they were N-glycosylated and bound to the yeast homolog of BiP, Kar2p. Similar to mutant yeast carboxypeptidase Y (CPY*), known to undergo cytosolic degradation, μ protein is stabilized in yeast mutants lacking the ubiquitinating enzymes Ubc6p and Ubc7p or in cells overexpressing mutant ubiquitin. Unexpectedly, the translation inhibitor cycloheximide (CHX), but not puromycin, led to the accumulation of polyubiquitinated μ chains that were still glycosylated. By contrast, degradation of CPY* was not impaired by CHX, indicating that the drug affects a substrate-specific degradation step. In contrast to the situation for CPY*, the ER-transmembrane protein Der1p is not essential for μ degradation. Strikingly, however, the CHX-induced accumulation of polyubiquitinated Igμ chains was stronger in ∆der1-mutants as compared to wild-type cells, indicating an additive effect of two inhibitory conditions. The results support a previously unknown activity of CHX, i.e. impairing the degradation of transport-incompetent secretory μ chains. Moreover, this activity will allow to dissect substrate-specific steps in ER associated protein degradation.
Copyright © 1999 by Walter de Gruyter GmbH & Co. KG
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Articles in the same Issue
- To Our Authors, Readers and Subscribers
- Michael Strauss. January 12, 1950 April 29, 1999
- Monoallelic Expression of Pax5: A Paradigm for the Haploinsufficiency of Mammalian Pax Genes?
- Adeno-Associated Viral Vectors for Gene Transfer and Gene Therapy
- Histidyl-tRNA Synthetase
- Dequalinium TM Vesicles Form Stable Complexes with Plasmid DNA which Are Protected from DNase Attack
- On the Role of Thymopoietins in Cell Proliferation. Immunochemical Evidence for New Members of the Human Thymopoietin Family
- Functional Characterization of Atherosclerosis-Associated Ser128Arg and Leu554Phe E-Selectin Mutations
- Cycloheximide, a New Tool to Dissect Specific Steps in ER-Associated Degradation of Different Substrates
- Localization of Rat Cathepsin K in Osteoclasts and Resorption Pits: Inhibition of Bone Resorption and Cathepsin K-Activity by Peptidyl Vinyl Sulfones
- Oxidation of 4-tert-Butylcatechol and Dopamine by Hydrogen Peroxide Catalysed by Horseradisch Peroxidase
- A Non-Radioactive Method for Inexpensive Quantitative RT-PCR
- Activation of the Transcription Factor ISGF3 by Interferon-gamma
- Acquisition of Myogenic Specificity through Replacement of One Amino Acid of MASH-1 and Introduction of an Additional alpha -Helical Turn
- The Heavy Metal-Responsive Transcription Factor-1 (MTF-1) Is Not Required for Neural Differentiation
- Human Fc gamma Receptor IIb Expressed in <I>Escherichia coli</I> Reveals IgG Binding Capability
- Mutational Analysis of Two Stefin A Epitopes
