Dfm1 forms distinct complexes with Cdc48 and the ER ubiquitin ligases and is required for ERAD

Traffic. 2010 Oct;11(10):1363-9. doi: 10.1111/j.1600-0854.2010.01093.x.

Abstract

Proteins imported into the endoplasmic reticulum (ER) are scanned for their folding status. Those that do not reach their native conformation are degraded via the ubiquitin-proteasome system. This process is called ER-associated degradation (ERAD). Der1 is known to be one of the components required for efficient degradation of soluble ERAD substrates like CPY(*) (mutated carboxypeptidase yscY). A homologue of Der1 exists, named Dfm1. No function of Dfm1 has been discovered, although a C-terminally hemagglutinin (HA)(3)-tagged Dfm1 protein has been shown to interact with the ERAD machinery. In our studies, we found Dfm1-HA(3) to be an ERAD substrate and therefore not suitable for functional studies of Dfm1 in ERAD. We found cellular, non-tagged Dfm1 to be a stable protein. We identified Dfm1 to be part of complexes which contain the ERAD-L ligase Hrd1/Der3 and Der1 as well as the ERAD-C ligase Doa10. In addition, ERAD of Ste6(*)-HA(3) was strongly dependent on Dfm1. Interestingly, Dfm1 forms a complex with the AAA-ATPase Cdc48 in a strain lacking the Cdc48 membrane-recruiting component Ubx2. This complex does not contain the ubiquitin ligases Hrd1/Der3 and Doa10. The existence of such a complex might point to an additional function of Dfm1 independent from ERAD.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Triphosphatases / genetics
  • Adenosine Triphosphatases / metabolism*
  • Carrier Proteins / genetics
  • Cell Cycle Proteins / genetics
  • Cell Cycle Proteins / metabolism*
  • Endoplasmic Reticulum / metabolism*
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism*
  • Proteasome Endopeptidase Complex / metabolism
  • Saccharomyces cerevisiae / metabolism*
  • Saccharomyces cerevisiae Proteins / genetics
  • Saccharomyces cerevisiae Proteins / metabolism*
  • Ubiquitin-Protein Ligases / metabolism*
  • Valosin Containing Protein

Substances

  • Carrier Proteins
  • Cell Cycle Proteins
  • DER1 protein, S cerevisiae
  • Dfm1 protein, S cerevisiae
  • Membrane Proteins
  • Saccharomyces cerevisiae Proteins
  • Usa1 protein, S cerevisiae
  • HRD1 protein, S cerevisiae
  • SSM4 protein, S cerevisiae
  • Ubiquitin-Protein Ligases
  • Proteasome Endopeptidase Complex
  • Adenosine Triphosphatases
  • CDC48 protein, S cerevisiae
  • Valosin Containing Protein