Ashkin A, Schütze K, Dziedzic J M, Euteneuer U, Schliwa M
Laser Science Research Department, AT&T Bell Laboratories, Holmdel, New Jersey 07733.
Nature. 1990 Nov 22;348(6299):346-8. doi: 10.1038/348346a0.
Organelle transport along microtubules is believed to be mediated by organelle-associated force-generating molecules. Two classes of microtubule-based organelle motors have been identified: kinesin and cytoplasmic dynein. To correlate the mechanochemical basis of force generation with the in vivo behaviour of organelles, it is important to quantify the force needed to propel an organelle along microtubules and to determine the force generated by a single motor molecule. Measurements of force generation are possible under selected conditions in vitro, but are much more difficult using intact or reactivated cells. Here we combine a useful model system for the study of organelle transport, the giant amoeba Reticulomyxa, with a novel technique for the non-invasive manipulation of and force application to subcellular components, which is based on a gradient-force optical trap, also referred to as 'optical tweezers'. We demonstrate the feasibility of using controlled manipulation of actively translocating organelles to measure direct force. We have determined the force driving a single organelle along microtubules, allowing us to estimate the force generated by a single motor to be 2.6 x 10(-7) dynes.
沿微管的细胞器运输被认为是由细胞器相关的力产生分子介导的。已鉴定出两类基于微管的细胞器马达：驱动蛋白和细胞质动力蛋白。为了将力产生的机械化学基础与细胞器的体内行为相关联，量化沿微管推动细胞器所需的力并确定单个马达分子产生的力非常重要。在体外选定条件下可以测量力的产生，但使用完整或再活化的细胞则困难得多。在这里，我们将用于研究细胞器运输的有用模型系统——巨型变形虫网柄菌，与一种基于梯度力光阱（也称为“光镊”）的对亚细胞成分进行非侵入性操纵和施加力的新技术相结合。我们证明了使用对主动转运细胞器的受控操纵来测量直接力的可行性。我们已经确定了驱动单个细胞器沿微管移动的力，从而使我们能够估计单个马达产生的力为2.6×10^(-7)达因。
