Human HRD1 Is an E3 Ubiquitin Ligase Involved in Degradation of Proteins from the Endoplasmic Reticulum

Marjolein Kikkert, Ram Doolman, Min Dai, Rachel Avner, Gerco Hassink, Sjaak Van Voorden, Swapna Thanedar, Joseph Roitelman, Vincent Chau, Emmanuel Wiertz

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Abstract

The ubiquitin system plays an important role in endoplasmic reticulum (ER)-associated degradation of proteins that are misfolded, that fail to associate with their oligomerization partners, or whose levels are metabolically regulated. E3 ubiquitin ligases are key enzymes in the ubiquitination process as they recognize the substrate and facilitate coupling of multiple ubiquitin units to the protein that is to be degraded. The Saccharomyces cerevisiae ER-resident E3 ligase Hrd1p/Der3p functions in the metabolically regulated degradation of 3-hydroxy-3-methylglutaryl-coenzyme A reductase and additionally facilitates the degradation of a number of misfolded proteins from the ER. In this study we characterized the structure and function of the putative human orthologue of yeast Hrd1p/Der3p, designated human HRD1. We show that human HRD1 is a non-glycosylated, stable ER protein with a cytosolic RING-H2 finger domain. In the presence of the ubiquitin-conjugating enzyme UBC7, the RING-H2 finger has in vitro ubiquitination activity for Lys48-specific polyubiquitin linkage, suggesting that human HRD1 is an E3 ubiquitin ligase involved in protein degradation. Human HRD1 appears to be involved in the basal degradation of 3-hydroxy-3-methylglutaryl-coenzyme A reductase but not in the degradation that is regulated by sterols. Additionally we show that human HRD1 is involved in the elimination of two model ER-associated degradation substrates, TCR-α and CD3-δ.

Original languageEnglish (US)
Pages (from-to)3525-3534
Number of pages10
JournalJournal of Biological Chemistry
Volume279
Issue number5
DOIs
Publication statusPublished - Jan 30 2004

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All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology
  • Cell Biology

Cite this

Kikkert, M., Doolman, R., Dai, M., Avner, R., Hassink, G., Van Voorden, S., ... Wiertz, E. (2004). Human HRD1 Is an E3 Ubiquitin Ligase Involved in Degradation of Proteins from the Endoplasmic Reticulum. Journal of Biological Chemistry, 279(5), 3525-3534. https://doi.org/10.1074/jbc.M307453200