Ubiquitination regulates proteolytic processing of G protein-coupled receptors after their sorting to lysosomes

James N. Hislop*, Anastasia G. Henry, Adriano Marchese, Mark von Zastrow

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

64 Citations (Scopus)

Abstract

Ubiquitination is essential for the endocytic sorting of various G protein-coupled receptors to lysosomes. Here we identify a distinct function of this covalent modification in controlling the later proteolytic processing of receptors. Mutation of all cytoplasmic lysine residues in the murine delta-opioid receptor blocked receptor ubiquitination without preventing ligand-induced endocytosis of receptors or their subsequent delivery to lysosomes, as verified by proteolysis of extramembrane epitope tags and down-regulation of radioligand binding to the transmembrane helices. Surprisingly, a functional screen revealed that the E3 ubiquitin ligase AIP4 specifically controls down-regulation of wild type receptors measured by radioligand binding without detectably affecting receptor delivery to lysosomes defined both immunochemically and biochemically. This specific AIP4-dependent regulation required direct ubiquitination of receptors and was also regulated by two deubiquitinating enzymes, AMSH and UBPY, which localized to late endosome/lysosome membranes containing internalized delta-opioid receptor. These results identify a distinct function of AIP4-dependent ubiquitination in controlling the later proteolytic processing of G protein-coupled receptors, without detectably affecting their endocytic sorting to lysosomes. We propose that ubiquitination or ubiquitination/deubiquitination cycling specifically regulates later proteolytic processing events required for destruction of the receptor's hydrophobic core.

Original languageEnglish
Pages (from-to)19361-19370
Number of pages10
JournalThe Journal of Biological Chemistry
Volume284
Issue number29
Early online date11 May 2009
DOIs
Publication statusPublished - 17 Jul 2009

Keywords

  • endoplasmic-reticulum
  • mediates ubiquitination
  • multivesicular body pathway
  • CXCR4
  • BETA(2)-adrenergic receptor
  • induced down-regulation
  • proteasome
  • molecular-mechanisms
  • endocytic membrane trafficking
  • delta-opioid receptor

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