A systematic search for endoplasmic reticulum (ER) membrane-associated RING finger proteins identifies Nixin/ZNRF4 as a regulator of calnexin stability and ER homeostasis

J Biol Chem. 2011 Mar 11;286(10):8633-8643. doi: 10.1074/jbc.M110.197459. Epub 2011 Jan 4.

Abstract

To identify novel regulators of endoplasmic reticulum (ER)-linked protein degradation and ER function, we determined the entire inventory of membrane-spanning RING finger E3 ubiquitin ligases localized to the ER. We identified 24 ER membrane-anchored ubiquitin ligases and found Nixin/ZNRF4 to be central for the regulation of calnexin turnover. Ectopic expression of wild type Nixin induced a dramatic down-regulation of the ER-localized chaperone calnexin that was prevented by inactivation of the Nixin RING domain. Importantly, Nixin physically interacts with calnexin in a glycosylation-independent manner, induces calnexin ubiquitination, and p97-dependent degradation, indicating an ER-associated degradation-like mechanism of calnexin turnover.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Calnexin / genetics
  • Calnexin / metabolism*
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism*
  • Down-Regulation / physiology*
  • Endoplasmic Reticulum / genetics
  • Endoplasmic Reticulum / metabolism*
  • Glycosylation
  • HeLa Cells
  • Humans
  • Protein Stability

Substances

  • DNA-Binding Proteins
  • ZNRF4 protein, human
  • Calnexin