Left–right (LR) asymmetry is crucial for animal development, particularly in Drosophila where LR‐asymmetric morphogenesis of organs hinges on cellular‐level chirality, termed cell chirality. In this species, two class I myosins, Myosin1D (Myo1D), and Myosin1C (Myo1C), respectively determine dextral (wild type) and sinistral (mirror image) cell chirality. Previous studies demonstrated Myo1D's ability to propel F‐actin in leftward circles during in vitro gliding assays, suggesting its mechanochemical role in defining dextral chirality. Conversely, Myo1C propels F‐actin without exhibiting LR‐directional preference in this assay, suggesting at other properties governing sinistral chirality. Given the interaction of Myo1D and Myo1C with the membrane, we hypothesized that differences in their membrane behaviors might be critical in dictating their dextral or sinistral activities. In this study, employing single‐molecule imaging analyses, we investigated the dynamic behaviors of Myo1D and Myo1C on the plasma membrane. Our findings revealed that Myo1C exhibits a significantly greater proportion of slow‐diffusing population compared to Myo1D. Importantly, this characteristic was contingent upon both head and tail domains of Myo1C. The distinct diffusion patterns of Myo1D and Myo1C did not exert mutual influence on each other. This divergence in membrane diffusion between Myo1D and Myo1C may be crucial for dictating cell and organ chirality.

中文翻译：

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左右肌球蛋白-Is、肌球蛋白1C 和肌球蛋白1D 在果蝇巨噬细胞质膜上表现出不同的单分子行为

左右（LR）不对称对于动物发育至关重要，特别是在果蝇其中器官的 LR 不对称形态发生取决于细胞水平的手性，称为细胞手性。在该物种中，两种 I 类肌球蛋白 Myosin1D (Myo1D) 和 Myosin1C (Myo1C) 分别决定右旋（野生型）和左旋（镜像）细胞手性。先前的研究表明，Myo1D 在体外滑动实验中能够推动 F-肌动蛋白向左旋转，表明其在定义右旋手性方面的机械化学作用。相反，Myo1C 在此测定中推动 F-肌动蛋白，但没有表现出 LR 方向偏好，这表明具有控制左旋手性的其他特性。鉴于 Myo1D 和 Myo1C 与膜的相互作用，我们假设它们的膜行为差异可能对于决定它们的右旋或左旋活动至关重要。在本研究中，我们采用单分子成像分析，研究了 Myo1D 和 Myo1C 在质膜上的动态行为。我们的研究结果表明，与 Myo1D 相比，Myo1C 的慢扩散群体比例明显更高。重要的是，这一特征取决于 Myo1C 的头部和尾部结构域。Myo1D 和 Myo1C 不同的扩散模式不会相互影响。Myo1D 和 Myo1C 之间膜扩散的差异可能对于决定细胞和器官的手性至关重要。