ArfGAP1 generates an Arf1 gradient on continuous lipid membranes displaying flat and curved regions

作者：Ambroggio Ernesto; Sorre Benoit; Bassereau Patricia; Goud Bruno^*; Manneville Lean Baptiste; Antonny Bruno

来源：The EMBO Journal, 2010, 29(2): 292-303.

DOI：10.1038/emboj.2009.341

• ALPS motif
• diffusion
• membrane curvature
• membrane tube
• optical tweezers

ArfGAP1, which promotes GTP hydrolysis on the small G protein Arf1 on Golgi membranes, interacts preferentially with positively curved membranes through its amphipathic lipid packing sensor (ALPS) motifs. This should influence the distribution of Arf1-GTP when flat and curved regions coexist on a continuous membrane, notably during COPI vesicle budding. To test this, we pulled tubes from giant vesicles using molecular motors or optical tweezers. Arf1-GTP distributed on the giant vesicles and on the tubes, whereas ArfGAP1 bound exclusively to the tubes. Decreasing the tube radius revealed a threshold of R approximate to 35 nm for the binding of ArfGAP1 ALPS motifs. Mixing catalytic amounts of ArfGAP1 with Arf1-GTP induced a smooth Arf1 gradient along the tube. This reflects that Arf1 molecules leaving the tube on GTP hydrolysis are replaced by new Arf1-GTP molecules diffusing from the giant vesicle. The characteristic length of the gradient is two orders of magnitude larger than a COPI bud, suggesting that Arf1-GTP diffusion can readily compensate for the localized loss of Arf1 during budding and contribute to the stability of the coat until fission. The EMBO Journal (2010) 29, 292-303. doi: 10.1038/emboj.2009.341; Published online 19 November 2009

• 出版日期2010-1-20