TOM1 is a PI5P effector involved in the regulation of endosomal maturation

J Cell Sci. 2015 Feb 15;128(4):815-27. doi: 10.1242/jcs.166314. Epub 2015 Jan 14.


Phosphoinositides represent a major class of lipids specifically involved in the organization of signaling cascades, maintenance of the identity of organelles and regulation of multiple intracellular trafficking steps. We previously reported that phosphatidylinositol 5-monophosphate (PI5P), produced by the Shigella flexneri phosphatase IpgD, is implicated in the endosomal sorting of the epidermal growth factor receptor (EGFR). Here, we show that the adaptor protein TOM1 is a new direct binding partner of PI5P. We identify the domain of TOM1 involved in this interaction and characterize the binding motif. Finally, we demonstrate that the recruitment of TOM1 by PI5P on signaling endosomes is responsible for the delay in EGFR degradation and fluid-phase bulk endocytosis. Taken together, our data strongly suggest that PI5P enrichment in signaling endosomes prevents endosomal maturation through the recruitment of TOM1, and point to a new function of PI5P in regulating discrete maturation steps in the endosomal system.

Keywords: EGFR; Phosphoinositides; Signaling endosome; TOM1; VHS domain.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Binding Sites
  • Cell Line
  • Cloning, Molecular
  • Cricetinae
  • Endocytosis / genetics
  • Endocytosis / physiology
  • Endosomes / metabolism*
  • ErbB Receptors / metabolism*
  • Fibroblasts
  • HeLa Cells
  • Humans
  • Mice
  • Mutagenesis, Site-Directed
  • Phosphatidylinositol Phosphates / metabolism*
  • Protein Binding
  • Protein Structure, Tertiary
  • Protein Transport
  • Proteins / genetics
  • Proteins / metabolism*
  • RNA Interference
  • RNA, Small Interfering
  • Signal Transduction


  • Phosphatidylinositol Phosphates
  • Proteins
  • RNA, Small Interfering
  • TOM1 protein, human
  • phosphatidylinositol 5-phosphate
  • EGFR protein, human
  • ErbB Receptors