Holmes K C, Tirion M, Popp D, Lorenz M, Kabsch W, Milligan R A
Department of Biophysics, Max Planck Institute for Medical Research, Heidelberg, Germany.
Adv Exp Med Biol. 1993;332:15-22; discussion 22-4. doi: 10.1007/978-1-4615-2872-2_2.
We compare the atomic model calculated from the crystal structure and the X-ray fiber diagram of orientated F-actin1) with the 3-D reconstructions produced from cryo-electron microscopy of actin2). Out to 30A resolution the two structures are essentially identical. Furthermore, by combining the atomic model with the reconstruction of S1-decorated actin filaments2) one can establish the nature of the actin binding site for myosin in the rigor complex. Each myosin head binds to two actin molecules on two distinct sites. Some of the actin residues involved in each of these binding sites can be identified. Furthermore, the atomic model of actin may be combined with the reconstruction of the S1 decorated thin filament to establish the tropomyosin binding site in the rigor complex. This result is compared with the model of tropomyosin-actin derived from an analysis of the X-ray fibre diagram of a reconstituted thin filament and are shown to be very similar.
我们将根据晶体结构和定向F-肌动蛋白的X射线纤维图计算出的原子模型与通过肌动蛋白的冷冻电子显微镜三维重建结果进行比较。在30埃分辨率范围内，这两种结构基本相同。此外，通过将原子模型与S1修饰的肌动蛋白丝的重建结果相结合，可以确定僵直复合物中肌球蛋白的肌动蛋白结合位点的性质。每个肌球蛋白头部在两个不同的位点与两个肌动蛋白分子结合。可以确定参与这些结合位点的一些肌动蛋白残基。此外，肌动蛋白的原子模型可以与S1修饰的细肌丝的重建结果相结合，以确定僵直复合物中的原肌球蛋白结合位点。将该结果与通过对重组细肌丝的X射线纤维图分析得出的原肌球蛋白-肌动蛋白模型进行比较，发现它们非常相似。
