The GTP switch of the small G-protein Arf1 (ADP-ribosylation factor 1) on lipid membranes promotes the polymerization of the COPI (coat protein complex I) coat, which acts as a membrane deforming shell to form transport vesicles. Real-time measurements for coat assembly on liposomes gives insights into how the GTPase cycle of Arf1 is coupled in time with the polymerization of the COPI coat and the resulting membrane deformation. One key parameter seems to be the membrane curvature. Arf-GAP1 (where GAP stands for GTPase-activating protein), which promotes GTP hydrolysis in the Arf1–COPI complex is highly sensitive to lipid packing. Its activity on Arf1-GTP increases by two orders of magnitude as the diameter of the liposomes approaches that of authentic transport vesicles (60 nm). This suggests that during membrane budding, Arf1-GTP molecules are progressively eliminated from the coated area where the membrane curvature is positive, but are protected from Arf-GAP1 at the bud neck due to the negative curvature of this region. As a result, the coat should be stable as long as the bud remains attached and should disassemble as soon as membrane fission occurs.
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August 2005
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Conference Article|
August 01 2005
Membrane curvature and the control of GTP hydrolysis in Arf1 during COPI vesicle formation
B. Antonny;
B. Antonny
1
1Institut de Pharmacologie Moléculaire et Cellulaire, CNRS et Université de Nice, 660 Route des Lucioles, 06560 Valbonne Sophia-Antipolis, France
1To whom correspondence should be addressed (email antonny@ipmc.cnrs.fr).
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J. Bigay;
J. Bigay
1Institut de Pharmacologie Moléculaire et Cellulaire, CNRS et Université de Nice, 660 Route des Lucioles, 06560 Valbonne Sophia-Antipolis, France
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J.-F. Casella;
J.-F. Casella
1Institut de Pharmacologie Moléculaire et Cellulaire, CNRS et Université de Nice, 660 Route des Lucioles, 06560 Valbonne Sophia-Antipolis, France
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G. Drin;
G. Drin
1Institut de Pharmacologie Moléculaire et Cellulaire, CNRS et Université de Nice, 660 Route des Lucioles, 06560 Valbonne Sophia-Antipolis, France
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B. Mesmin;
B. Mesmin
1Institut de Pharmacologie Moléculaire et Cellulaire, CNRS et Université de Nice, 660 Route des Lucioles, 06560 Valbonne Sophia-Antipolis, France
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P. Gounon
P. Gounon
1Institut de Pharmacologie Moléculaire et Cellulaire, CNRS et Université de Nice, 660 Route des Lucioles, 06560 Valbonne Sophia-Antipolis, France
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Publisher: Portland Press Ltd
Received:
February 22 2005
Online ISSN: 1470-8752
Print ISSN: 0300-5127
© 2005 The Biochemical Society
2005
Biochem Soc Trans (2005) 33 (4): 619–622.
Article history
Received:
February 22 2005
Citation
B. Antonny, J. Bigay, J.-F. Casella, G. Drin, B. Mesmin, P. Gounon; Membrane curvature and the control of GTP hydrolysis in Arf1 during COPI vesicle formation. Biochem Soc Trans 1 August 2005; 33 (4): 619–622. doi: https://doi.org/10.1042/BST0330619
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