An FTS/Hook/p107(FHIP) complex interacts with and promotes endosomal clustering by the homotypic vacuolar protein sorting complex

Mol Biol Cell. 2008 Dec;19(12):5059-71. doi: 10.1091/mbc.e08-05-0473. Epub 2008 Sep 17.


Fused Toes (FTS) is a member of a small group of inactive variant E2 ubiquitin-conjugating enzyme domain-containing proteins of unknown function. Through proteomic analysis of FTS complexes purified from human embryonic kidney 293T cells, we identified a new multiprotein complex, the FHF complex, containing FTS, members of the microtubule-binding Hook family of coiled-coil proteins (Hook1, Hook2, and Hook3), and a previously uncharacterized 107-kDa protein, FTS and Hook Interacting Protein (FHIP). FTS associated with a conserved C-terminal motif in Hook proteins in the yeast two-hybrid system and in tissue culture cells, and Hook proteins were found to form homo- and heterodimers. The approximately 500-kDa FHF complex contained all three Hook proteins, and small interfering RNA depletion experiments suggest that Hook proteins can interact interchangeably within this complex. Hook proteins as well as FTS interact with members of both the class B and class C components of the homotypic vesicular protein sorting (HOPS) complex. Depletion of FTS by RNA interference affects both the trafficking of epidermal growth factor from early-to-late endosome/lysosomes and the efficiency by which overexpression of the HOPS component Vps18 promotes clustering of lysosomal-associated membrane protein 1-positive endosome/lysosomes. These data suggest that the FTS/Hook/FHIP complex functions to promote vesicle trafficking and/or fusion via the HOPS complex.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptor Proteins, Signal Transducing / genetics
  • Adaptor Proteins, Signal Transducing / metabolism*
  • Amino Acid Sequence
  • Animals
  • Apoptosis Regulatory Proteins / genetics
  • Apoptosis Regulatory Proteins / metabolism*
  • Cell Line
  • Endosomes / metabolism*
  • Humans
  • Lysosomes / metabolism
  • Mice
  • Microtubule-Associated Proteins / genetics
  • Microtubule-Associated Proteins / metabolism*
  • Models, Molecular
  • Molecular Sequence Data
  • Multiprotein Complexes / metabolism*
  • Protein Conformation
  • Protein Isoforms / genetics
  • Protein Isoforms / metabolism
  • Protein Transport
  • RNA Interference
  • Retinoblastoma-Like Protein p107 / genetics
  • Retinoblastoma-Like Protein p107 / metabolism*
  • Sequence Alignment
  • Ubiquitin-Conjugating Enzymes / chemistry
  • Ubiquitin-Conjugating Enzymes / genetics
  • Ubiquitin-Conjugating Enzymes / metabolism
  • Vacuoles / metabolism*


  • AKTIP protein, human
  • Adaptor Proteins, Signal Transducing
  • Apoptosis Regulatory Proteins
  • Microtubule-Associated Proteins
  • Multiprotein Complexes
  • Protein Isoforms
  • Retinoblastoma-Like Protein p107
  • hook1 protein, human
  • UBE2D1 protein, human
  • Ubiquitin-Conjugating Enzymes