Abstract
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.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.