ArfGAP1 generates an Arf1 gradient on continuous lipid membranes displaying flat and curved regions
ArfGAP1 generates an Arf1 gradient on continuous lipid membranes displaying flat and curved regions
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DOI：
10.1038/emboj.2009.341
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发表时间：
2010-01-20
期刊：
影响因子：
11.4
通讯作者：
Antonny, Bruno
中科院分区：
文献类型：
--
作者：
Ambroggio, Ernesto;Sorre, Benoit;Antonny, Bruno
ArfGAP 1促进高尔基体膜上小G蛋白Arf 1上的GTP水解，通过其两亲性脂质包装传感器（ALPS）基序优先与正弯曲膜相互作用。这应该会影响Arf 1-GTP的分布时，平坦和弯曲的地区共存于一个连续的膜，特别是在COPI囊泡出芽。为了验证这一点，我们用分子马达或光镊从巨大的囊泡中拉出了管子。Arf 1-GTP分布在巨囊泡和微管上，而ArfGAP 1仅与微管结合。减小管半径揭示了ArfGAP 1 ALPS基序结合的R阈值约为35 nm。将催化量的ArfGAP 1与Arf 1-GTP混合诱导沿管沿着平滑的Arf 1梯度。这反映了在GTP水解时离开管的Arf 1分子被从巨囊泡扩散的新Arf 1-GTP分子所取代。梯度的特征长度比COPI芽大两个数量级，表明Arf 1-GTP扩散可以很容易地补偿出芽过程中Arf 1的局部损失，并有助于外套的稳定性，直到分裂。The EMBO Journal（2010）29，292-303. doi：10.1038/doj.2009.341; 2009年11月19日在线发布
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