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Proteasomal degradation of misfolded proteins

Authors

  • R. Gauss
  • O. Neuber
  • T. Sommer

Citation

  • 185-220

Abstract

  • One of the most important functions of cellular quality control systems is to maintain structural fidelity of proteins. Molecular chaperones prevent aggregation and assist folding of newly synthesized proteins in the cytosol and the ER. Furthermore, in concert with ubiquitin-ligases, chaperones detect misfolded or damaged proteins and target them for degradation by the ubiquitin-proteasome system. Some U-box ligases link recognition of aberrant cytosolic proteins to degradation. In degradation of malfolded secretory proteins from the ER, recognition by chaperones is separated from the ubiquitin-proteasome system by the ER-membrane. Therefore, dislocation precedes ubiquitination mediated by two RING-finger ligases in the ER membrane. Proteins are marked for degradation by the attachment of poly-ubiquitin chains. Poly-ubiquitinated proteins are subsequently recognized by a Cdc48p/p97 complex and delivered to the proteasome where they are degraded. Malfunction of protein degradation by the ubiquitin-proteasome system leads to the generation of severe human diseases.


DOI

doi:10.1007/4735_90