Membrane curvature has emerged as an intriguing physical organization principle underlying biological signaling and membrane trafficking. FBP17 of the CIP4/FBP17/Toca-1 F-BAR family is unique in the BAR family because its structurally folded F-BAR domain does not contain any hydrophobic motifs that insert into lipid bilayer. While it has been widely assumed so, whether the banana-shaped F-BAR domain alone can sense curvature has never been experimentally demonstrated. Using a nanopillar-supported lipid bilayer system, we found that the F-BAR domain of FBP17 displayed minimal curvature sensing in vitro. We further identified an alternatively spliced intrinsically disordered region (IDR) of FBP17 next to its F-BAR domain that is conserved in sequence across species. The IDR senses membrane curvature and its sensing ability greatly exceeds that of F-BAR domain alone. In living cells, presence of the IDR domain changed the dynamics of FBP17 recruitment in a curvature-coupled cortical wave system. Collectively, we propose that FBP17 does sense curvature but contrary to the common belief, its curvature sensing capability largely originates from its disordered region, not F-BAR domain itself.

中文翻译：

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F-BAR域和FBP17的本征无序区域介导的曲率传感的比较研究

膜曲率已经成为生物学信号和膜运输基础上一个有趣的物理组织原理。CIP4 / FBP17 / Toca-1 F-BAR家族的FBP17在BAR家族中是独一无二的，因为其结构折叠的F-BAR结构域不包含任何插入脂质双层中的疏水性基序。尽管已被广泛假定，但是从未单独通过实验证明香蕉形F-BAR域是否可以感知曲率。使用纳米柱支持的脂质双层系统，我们发现FBP17的F-BAR域在体外显示出最小的曲率感测。我们进一步确定FBP17的另一个剪接的内在无序区（IDR），紧邻其F-BAR域，该序列在整个物种中均保守。IDR感应膜曲率，其感应能力大大超过了单独的F-BAR域。在活细胞中，IDR域的存在改变了曲率耦合皮层波系统中FBP17募集的动力学。总的来说，我们提出FBP17确实可以感应曲率，但是与通常的看法相反，它的曲率感应能力主要源自其无序区域，而不是F-BAR域本身。