Departmental Bulletin Paper Translocation of cationic polystyrene microspheres associated with actin filaments on a surface coated with myosin motors

OYAMA, Takuya  ,  HATORI, Kuniyuki

Muscular actin filaments can glide on a myosin-fixed glass surface by mechanochemical energy transduction. Here, we examined whether artificial objects bound to actin filaments can be translocated actively by myosin motors. Actin molecules may have a monomeric (G-actin) or fibrous form (F-actin), depending on the ionic conditions. Each form of actin molecules was mixed with a suspension of polystyrene microspheres carrying amine groups. After myosin motors were fixed on the collodion-coated glass surface, the mixture of actin molecules and microspheres was applied in the presence of adenosine triphosphate. The motion of the microspheres was monitored under a phase-contrast optical microscope. The microspheres mixed with G-actin exhibited thermal fluctuations due to insufficient binding of G-actin. In contrast, F-actin could bind to the microspheres and they were translocated in linear manner at approximately 1.5 μm/s on the myosin-coated surface. These results demonstrate that the actin filaments bound to polystyrene microspheres are capable of translocation between the actin and myosin.

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