Takeuchi K, Ishimura K
J Biochem. 1985 Jun;97(6):1695-708. doi: 10.1093/oxfordjournals.jbchem.a135228.
Porcine platelet myosin molecules were examined by electron microscopy for changes in their shape. At high ionic strength, the molecules were morphologically indistinguishable from skeletal muscle myosin, except for a slight difference in the bent regions of their tails. At physiological ionic strength, however, the following important difference was observed between the two myosins. Unlike skeletal muscle myosin, the filaments of nonphosphorylated platelet myosin could be disassembled by stoichiometric ATP into a monomeric form with sharply bent or folded tail, and reassembled after ATP hydrolysis. Similar disassembly changes could be induced by various nucleotide triphosphates (CTP, GTP, ITP, and UTP) and to a lesser extent by ADP, AMP, and AMPPNP. These results suggest that ATP binds to the hydrolytic sites in platelet myosin molecule and induces the molecular shape change.
通过电子显微镜检查猪血小板肌球蛋白分子的形状变化。在高离子强度下，这些分子在形态上与骨骼肌肌球蛋白无法区分，只是其尾部弯曲区域略有不同。然而，在生理离子强度下，观察到两种肌球蛋白之间存在以下重要差异。与骨骼肌肌球蛋白不同，未磷酸化的血小板肌球蛋白细丝可被化学计量的ATP分解成具有急剧弯曲或折叠尾部的单体形式，并在ATP水解后重新组装。各种三磷酸核苷酸（CTP、GTP、ITP和UTP）也能诱导类似的分解变化，而ADP、AMP和AMPPNP的诱导作用较小。这些结果表明，ATP与血小板肌球蛋白分子中的水解位点结合并诱导分子形状改变。
