Kinesin superfamily protein UNC-104, a member of the kinesin-3 family, transports synaptic vesicle precursors (SVPs). In this study, the number of active UNC-104 molecules hauling a single SVP in axons in the worm Caenorhabditis elegans was counted by applying a newly developed non-invasive force measurement technique. The distribution of the force acting on a SVP transported by UNC-104 was spread out over several clusters, implying the presence of several force-producing units (FPUs). We then compared the number of FPUs in the wild-type worms with that in arl-8 gene-deletion mutant worms. ARL-8 is a SVP-bound arf-like small guanosine triphosphatase, and is known to promote unlocking of the autoinhibition of the motor, which is critical for avoiding unnecessary consumption of adenosine triphosphate when the motor does not bind to a SVP. There were fewer FPUs in the arl-8 mutant worms. This finding indicates that a lack of ARL-8 decreased the number of active UNC-104 motors, which then led to a decrease in the number of motors responsible for SVP transport.

中文翻译：

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无创力测量揭示了由ARL-8调节的轴突运输中突触小泡前体上活性驱动蛋白的数量†

Kinesin超家族蛋白UNC-104是kinesin-3家族的成员，可转运突触小泡前体（SVP）。在这项研究中，通过应用一种新开发的无创力测量技术，对线虫秀丽隐杆线虫的轴突中单个SVP进行拖拉的活性UNC-104分子数量进行了计数。作用在由UNC-104运送的SVP上的力的分布分布在几个群集上，这意味着存在多个制动力单元（FPU）。然后，我们将野生型蠕虫中的FPU数量与arl-8中的FPU数量进行了比较。基因缺失突变蠕虫。ARL-8是一种结合SVP的arf样小鸟苷三磷酸鸟苷，已知会促进电机自身抑制的解锁，这对于避免电机不与SVP结合时三磷酸腺苷的不必要消耗至关重要。arl-8突变蠕虫中的FPU较少。这一发现表明，缺少ARL-8会减少活动UNC-104电机的数量，从而导致负责SVP传输的电机数量减少。