Inter-organelle lipid transfer: a channel model for Vps13 and chorein-N motif proteins

Curr Opin Cell Biol. 2020 Aug:65:66-71. doi: 10.1016/j.ceb.2020.02.008. Epub 2020 Mar 23.

Abstract

Membrane contact sites, where two organelles are in close proximity, are critical regulators of cellular membrane homeostasis, with roles in signaling, lipid metabolism, and ion dynamics. A growing catalog of specialized lipid transfer proteins carry out lipid exchange at these sites. Currently characterized eukaryotic lipid transport proteins are shuttles that typically extract a single lipid from the membrane of the donor organelle, solubilize it during transport through the cytosol, and deposit it in the acceptor organelle membrane. Here, we highlight the recently identified chorein_N family of lipid transporters, including the Vps13 proteins and the autophagy protein Atg2. These are elongated proteins that, distinct from previously characterized transport proteins, bind tens of lipids at once. They feature an extended channel, most likely lined with hydrophobic residues. We discuss the possibility that they are not shuttles but instead are bridges between membranes, with lipids traversing the cytosol via the hydrophobic channel.

Keywords: Chorein_N motif; Lipid transfer proteins; Membrane contact sites.

Publication types

  • Research Support, N.I.H., Extramural
  • Review

MeSH terms

  • Carrier Proteins / metabolism
  • Humans
  • Lipid Metabolism*
  • Mitochondrial Membranes / metabolism
  • Models, Biological*
  • Organelles / metabolism*
  • Vesicular Transport Proteins / chemistry*
  • Vesicular Transport Proteins / metabolism*

Substances

  • Carrier Proteins
  • Vesicular Transport Proteins
  • lipid transfer protein