Drummond D R, Peckham M, Sparrow J C, White D C
Department of Biology, University of York, UK.
Nature. 1990 Nov 29;348(6300):440-2. doi: 10.1038/348440a0.
The generation of force during muscle contraction results from the interaction of myosin and actin. The kinetics of this force generation vary between different muscle types and within the same muscle type in different species. Most attention has focused on the role of myosin isoforms in determining these differences. The role of actin isoforms has received little attention, largely because of the lack of a suitable cell type in which the myosin isoform remains constant yet the actin isoforms vary. An alternative approach would be to examine the effect of actin mutations, however, most of these cause such gross disruption of muscle structure that mechanical measurements are impossible. We have now identified two actin mutations which, despite involving conserved amino acids, can assemble into virtually normal myofibrils. These amino-acid changes in actin significantly affect the kinetics of force generation by muscle fibres. One of the mutations is not in the putative myosin-binding site, demonstrating the importance of long-range effects of amino acids on actin function.
肌肉收缩过程中的力产生源于肌球蛋白和肌动蛋白的相互作用。这种力产生的动力学在不同肌肉类型之间以及同一肌肉类型在不同物种中有所不同。大多数注意力都集中在肌球蛋白同工型在决定这些差异中的作用。肌动蛋白同工型的作用很少受到关注，主要是因为缺乏一种合适的细胞类型，其中肌球蛋白同工型保持不变而肌动蛋白同工型有所不同。一种替代方法是检查肌动蛋白突变的影响，然而，这些突变中的大多数会导致肌肉结构的严重破坏，以至于无法进行力学测量。我们现在已经鉴定出两种肌动蛋白突变，尽管涉及保守氨基酸，但它们可以组装成几乎正常的肌原纤维。肌动蛋白中的这些氨基酸变化显著影响肌肉纤维产生力的动力学。其中一种突变不在假定的肌球蛋白结合位点，这证明了氨基酸对肌动蛋白功能的远程影响的重要性。
