VARP is recruited on to endosomes by direct interaction with retromer, where together they function in export to the cell surface

Dev Cell. 2014 Jun 9;29(5):591-606. doi: 10.1016/j.devcel.2014.04.010. Epub 2014 May 22.

Abstract

VARP is a Rab32/38 effector that also binds to the endosomal/lysosomal R-SNARE VAMP7. VARP binding regulates VAMP7 participation in SNARE complex formation and can therefore influence VAMP7-mediated membrane fusion events. Mutant versions of VARP that cannot bind Rab32:GTP, designed on the basis of the VARP ankyrin repeat/Rab32:GTP complex structure described here, unexpectedly retain endosomal localization, showing that VARP recruitment is not dependent on Rab32 binding. We show that recruitment of VARP to the endosomal membrane is mediated by its direct interaction with VPS29, a subunit of the retromer complex, which is involved in trafficking from endosomes to the TGN and the cell surface. Transport of GLUT1 from endosomes to the cell surface requires VARP, VPS29, and VAMP7 and depends on the direct interaction between VPS29 and VARP. Finally, we propose that endocytic cycling of VAMP7 depends on its interaction with VARP and, consequently, also on retromer.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Blotting, Western
  • Cell Membrane / metabolism*
  • Crystallography, X-Ray
  • Endosomes / physiology*
  • Glucose Transporter Type 1 / metabolism*
  • Guanine Nucleotide Exchange Factors / chemistry
  • Guanine Nucleotide Exchange Factors / genetics
  • Guanine Nucleotide Exchange Factors / metabolism*
  • Guanosine Triphosphate / metabolism
  • HeLa Cells
  • Humans
  • Immunoprecipitation
  • Molecular Sequence Data
  • Muscle Proteins / metabolism
  • Mutagenesis, Site-Directed
  • Nuclear Proteins / metabolism
  • Protein Binding
  • Protein Conformation
  • Protein Multimerization
  • Protein Transport
  • R-SNARE Proteins / chemistry
  • R-SNARE Proteins / genetics
  • R-SNARE Proteins / metabolism*
  • Repressor Proteins / metabolism
  • Sequence Homology, Amino Acid
  • Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
  • Vesicular Transport Proteins / chemistry
  • Vesicular Transport Proteins / genetics
  • Vesicular Transport Proteins / metabolism*
  • rab GTP-Binding Proteins / metabolism*

Substances

  • ANKRD1 protein, human
  • Glucose Transporter Type 1
  • Guanine Nucleotide Exchange Factors
  • Muscle Proteins
  • Nuclear Proteins
  • R-SNARE Proteins
  • Repressor Proteins
  • SLC2A1 protein, human
  • VAMP7 protein, human
  • VPS29 protein, human
  • Varp protein, human
  • Vesicular Transport Proteins
  • Guanosine Triphosphate
  • Rab32 protein, human
  • rab GTP-Binding Proteins

Associated data

  • PDB/4CYM