Lipid packing sensed by ArfGAP1 couples COPI coat disassembly to membrane bilayer curvature

Nature. 2003 Dec 4;426(6966):563-6. doi: 10.1038/nature02108.


Protein coats deform flat lipid membranes into buds and capture membrane proteins to form transport vesicles. The assembly/disassembly cycle of the COPI coat on Golgi membranes is coupled to the GTP/GDP cycle of the small G protein Arf1. At the heart of this coupling is the specific interaction of membrane-bound Arf1-GTP with coatomer, a complex of seven proteins that forms the building unit of the COPI coat. Although COPI coat disassembly requires the catalysis of GTP hydrolysis in Arf1 by a specific GTPase-activating protein (ArfGAP1), the precise timing of this reaction during COPI vesicle formation is not known. Using time-resolved assays for COPI dynamics on liposomes of controlled size, we show that the rate of ArfGAP1-catalysed GTP hydrolysis in Arf1 and the rate of COPI disassembly increase over two orders of magnitude as the curvature of the lipid bilayer increases and approaches that of a typical transport vesicle. This leads to a model for COPI dynamics in which GTP hydrolysis in Arf1 is organized temporally and spatially according to the changes in lipid packing induced by the coat.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • ADP-Ribosylation Factors / metabolism*
  • Animals
  • COP-Coated Vesicles / chemistry*
  • COP-Coated Vesicles / metabolism*
  • COP-Coated Vesicles / ultrastructure
  • Coat Protein Complex I / metabolism*
  • GTPase-Activating Proteins / metabolism*
  • Golgi Apparatus / chemistry
  • Guanosine Triphosphate / metabolism
  • Hydrolysis
  • Intracellular Membranes / chemistry
  • Kinetics
  • Lipid Bilayers / chemistry*
  • Lipid Bilayers / metabolism*
  • Lipid Metabolism*
  • Lipids / chemistry
  • Liposomes / chemistry
  • Liposomes / metabolism
  • Models, Biological
  • Rabbits
  • Time Factors


  • Coat Protein Complex I
  • GTPase-Activating Proteins
  • Lipid Bilayers
  • Lipids
  • Liposomes
  • Guanosine Triphosphate
  • ADP-Ribosylation Factors