Differential role of mannose and glucose trimming in the ER degradation of asialoglycoprotein receptor subunits

Michal Ayalon-Soffer, Marina Shenkman, Gerardo Z. Lederkremer

Research output: Contribution to journalArticlepeer-review

Abstract

To gain insight into how sugar chain processing events modulate endoplasmic reticulum (ER)/proteasomal degradation we looked at human asialoglycoprotein receptor polypeptides H2a and H2b, variants which differ only by an extra pentapeptide (EGHRG) present in H2a. Membrane-bound H2a is a precursor of a soluble secreted form while H2b reaches the plasma membrane. Uncleaved precursor H2a molecules are completely retained in the ER and degraded as well as a portion of H2b. Inhibition of N-linked sugar chain mannose trimming stabilized both variants. In contrast, inhibition of glucose trimming with castanospermine greatly enhanced the degradation rate of H2a but not that of H2b. We studied a possible involvement of the ER chaperone calnexin, as inhibitors of glucose trimming are known to prevent calnexin binding.

Original languageEnglish
Pages (from-to)3309-3318
Number of pages10
JournalJournal of Cell Science
Volume112
Issue number19
StatePublished - 1999

Keywords

  • Asialoglycoprotein receptor
  • Calnexin
  • Chaperone
  • Endoplasmic reticulum degradation
  • Glycosylation
  • Proteasome

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