The assembly of actin filaments into distinct cytoskeletal structures plays a critical role in cell physiology, but how proteins localize differentially to these structures within a shared cytoplasm remains unclear. Here, we show that the actin-binding domains of accessory proteins can be sensitive to filament conformational changes. Using a combination of live cell imaging and in vitro single molecule binding measurements, we show that tandem calponin homology domains (CH1–CH2) can be mutated to preferentially bind actin networks at the front or rear of motile cells. We demonstrate that the binding kinetics of CH1–CH2 domain mutants varies as actin filament conformation is altered by perturbations that include stabilizing drugs and other binding proteins. These findings suggest that conformational changes of actin filaments in cells could help to direct accessory binding proteins to different actin cytoskeletal structures through a biophysical feedback loop.

肌动蛋白丝组装成不同的细胞骨架结构在细胞生理学中起着至关重要的作用，但蛋白质如何在共享细胞质内差异定位到这些结构仍不清楚。在这里，我们证明辅助蛋白的肌动蛋白结合域可以对丝构象变化敏感。通过结合活细胞成像和体外单分子结合测量，我们发现串联钙调蛋白同源结构域（CH1-CH2）可以发生突变，以优先结合运动细胞前部或后部的肌动蛋白网络。我们证明，CH1-CH2 结构域突变体的结合动力学会随着肌动蛋白丝构象因稳定药物和其他结合蛋白等扰动而改变而变化。这些发现表明，细胞中肌动蛋白丝的构象变化可能有助于通过生物物理反馈回路将辅助结合蛋白引导至不同的肌动蛋白细胞骨架结构。