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Analysis of SNARE-mediated Membrane Fusion Using an Enzymatic Cell Fusion Assay
09:19

Analysis of SNARE-mediated Membrane Fusion Using an Enzymatic Cell Fusion Assay

Published on: October 19, 2012

A Ypt/Rab effector complex containing the Sec1 homolog Vps33p is required for homotypic vacuole fusion

D F Seals1, G Eitzen, N Margolis

  • 1Department of Biochemistry, Dartmouth Medical School, Hanover, NH 03755-3844, USA.

Proceedings of the National Academy of Sciences of the United States of America
|August 16, 2000
PubMed

Insights

Researchers identified the HOPS complex, crucial for yeast vacuole fusion. This complex links Vam2/6p and class C Vps proteins to Ypt7p, initiating the docking process for homotypic vacuole fusion.

Area of Science:

  • Cell biology
  • Molecular biology
  • Protein complex research

Background:

  • Yeast vacuole fusion involves priming, docking, and fusion stages.
  • Vam2p and Vam6p (Vam2/6p) are vacuole-associated proteins within a 65S complex containing SNAREs.
  • The precise connections between these fusion stages and protein complexes were not well understood.

Purpose of the Study:

  • To elucidate the connections between yeast vacuole priming, docking, and fusion.
  • To identify the composition and function of the 38S subcomplex released after priming.
  • To establish a mechanistic link between class C Vps proteins and Ypt/Rab proteins in vacuole fusion.

Main Methods:

  • Biochemical analysis of protein complexes involved in yeast vacuole fusion.
  • Characterization of the 38S subcomplex released upon priming by Sec18p/NSF and ATP.
  • Investigating the interaction of the 38S complex with Ypt7p and SNARE proteins.

Main Results:

  • The 38S subcomplex, released after priming, consists of Vam2/6p and class C Vps proteins, including Vps33p.
  • This 38S complex is named HOPS (homotypic fusion and vacuole protein sorting).
  • HOPS links Vam2/6p to SNAREs and connects class C Vps proteins to Ypt/Rab function, initiating docking by binding to Ypt7p.

Conclusions:

  • The HOPS complex provides a mechanistic link between vacuole priming and docking.
  • HOPS facilitates homotypic vacuole fusion by mediating the interaction between SNAREs and the Ypt7p GTPase.
  • This discovery clarifies the role of class C Vps proteins in Ypt/Rab-mediated membrane trafficking events.

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