The Png1-Rad23 complex regulates glycoprotein turnover

Ikjin Kim, Jungmi Ahn, Chang Liu, Kaori Tanabe, Jennifer Apodaca, Tadashi Suzuki, Hai Rao

Research output: Contribution to journalArticlepeer-review

104 Scopus citations


Misfolded proteins in the endoplasmic reticulum (ER) are destroyed by a pathway termed ER-associated protein degradation (ERAD). Glycans are often removed from glycosylated ERAD sub strates in the cytosol before substrate degradation, which maintains the efficiency of the proteasome. Png1, a deglycosylating enzyme, has long been suspected, but not proven, to be crucial in this process. We demonstrate that the efficient degradation of glycosylated ricin A chain re quires the Png1-Rad23 complex, suggesting that this complex couples protein deglycosylation and degradation. Rad23 is a ubiquitin (Ub) binding protein involved in the trans fer of ubiquitylated substrates to the proteasome. How Rad23 achieves its substrate specificity is unknown. We show that Rad23 binds various regulators of proteolysis to facilitate the degradation of distinct substrates. We propose that the substrate specificity of Rad23 and other Ub binding proteins is determined by their interactions with various cofactors involved in specific degradation pathways.

Original languageEnglish (US)
Pages (from-to)211-219
Number of pages9
JournalJournal of Cell Biology
Issue number2
StatePublished - Jan 16 2006

ASJC Scopus subject areas

  • Cell Biology


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