The ESCRT protein CHMP2B acts as a diffusion barrier on reconstituted membrane necks

J Cell Sci. 2018 Aug 3;132(4):jcs217968. doi: 10.1242/jcs.217968.


Endosomal sorting complexes required for transport (ESCRT)-III family proteins catalyze membrane remodeling processes that stabilize and constrict membrane structures. It has been proposed that stable ESCRT-III complexes containing CHMP2B could establish diffusion barriers at the post-synaptic spine neck. In order to better understand this process, we developed a novel method based on fusion of giant unilamellar vesicles to reconstitute ESCRT-III proteins inside GUVs, from which membrane nanotubes are pulled. The new assay ensures that ESCRT-III proteins polymerize only when they become exposed to physiologically relevant membrane topology mimicking the complex geometry of post-synaptic spines. We establish that CHMP2B, both full-length and with a C-terminal deletion (ΔC), preferentially binds to membranes containing phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2]. Moreover, we show that CHMP2B preferentially accumulates at the neck of membrane nanotubes, and provide evidence that CHMP2B-ΔC prevents the diffusion of PI(4,5)P2 lipids and membrane-bound proteins across the tube neck. This indicates that CHMP2B polymers formed at a membrane neck may function as a diffusion barrier, highlighting a potential important function of CHMP2B in maintaining synaptic spine structures.

Keywords: CHMP2B; Dendritic spine; ESCRT; GUV; Membrane fusion.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Chromosome Pairing / physiology
  • Diffusion
  • Endosomal Sorting Complexes Required for Transport / metabolism*
  • Escherichia coli
  • Membrane Proteins / metabolism*
  • Nerve Tissue Proteins / metabolism
  • Spine / metabolism
  • Unilamellar Liposomes / metabolism*


  • CHMP2B protein, human
  • Endosomal Sorting Complexes Required for Transport
  • Membrane Proteins
  • Nerve Tissue Proteins
  • Unilamellar Liposomes