Regulation of Ubiquitin-Binding Proteins by Monoubiquitination

Nat Cell Biol. 2006 Feb;8(2):163-9. doi: 10.1038/ncb1354. Epub 2006 Jan 22.

Abstract

Proteins containing ubiquitin-binding domains (UBDs) interact with ubiquitinated targets and regulate diverse biological processes, including endocytosis, signal transduction, transcription and DNA repair. Many of the UBD-containing proteins are also themselves monoubiquitinated, but the functional role and the mechanisms that underlie this modification are less well understood. Here, we demonstrate that monoubiquitination of the endocytic proteins Sts1, Sts2, Eps15 and Hrs results in intramolecular interactions between ubiquitin and their UBDs, thereby preventing them from binding in trans to ubiquitinated targets. Permanent monoubiquitination of these proteins, mimicked by the fusion of ubiquitin to their carboxyl termini, impairs their ability to regulate trafficking of ubiquitinated receptors. Moreover, we mapped the in vivo monoubiquitination site in Sts2 and demonstrated that its mutation enhances the Sts2-mediated effects of epidermal-growth-factor-receptor downregulation. We propose that monoubiquitination of ubiquitin-binding proteins inhibits their capacity to bind to and control the functions of ubiquitinated targets in vivo.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptor Proteins, Signal Transducing
  • Amino Acid Sequence
  • Calcium-Binding Proteins / genetics
  • Calcium-Binding Proteins / metabolism
  • Carrier Proteins / genetics
  • Carrier Proteins / metabolism
  • Carrier Proteins / physiology*
  • Cell Line
  • Endosomal Sorting Complexes Required for Transport
  • Endosomes / metabolism
  • ErbB Receptors / metabolism
  • Fluorescence Resonance Energy Transfer
  • Green Fluorescent Proteins / genetics
  • HeLa Cells
  • Humans
  • Intracellular Signaling Peptides and Proteins
  • Lysine / genetics
  • Lysine / metabolism
  • Membrane Proteins
  • Models, Molecular
  • Molecular Sequence Data
  • Mutation / genetics
  • Phosphoproteins / genetics
  • Phosphoproteins / metabolism
  • Protein Binding
  • Protein Tyrosine Phosphatases
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • Sequence Homology, Amino Acid
  • Transfection
  • Transferrin / metabolism
  • Ubiquitin / metabolism
  • Ubiquitin / physiology*

Substances

  • Adaptor Proteins, Signal Transducing
  • CLIP4 protein, human
  • Calcium-Binding Proteins
  • Carrier Proteins
  • Cyan Fluorescent Protein
  • EPS15 protein, human
  • Endosomal Sorting Complexes Required for Transport
  • Intracellular Signaling Peptides and Proteins
  • Membrane Proteins
  • Phosphoproteins
  • Recombinant Fusion Proteins
  • Transferrin
  • Ubiquitin
  • hepatocyte growth factor-regulated tyrosine kinase substrate
  • Green Fluorescent Proteins
  • ErbB Receptors
  • Protein Tyrosine Phosphatases
  • Sts-1 protein, human
  • Lysine