Fig. 3. Single myosin V molecules, imaged by total internal reflection microscopy, move along isolated actin filaments. Myosin V molecules are shown in green; actin is shown in red. Fluorophores appear to accumulate at the barbed filament end. This suggests that, when a single moving myosin V encounters a problem ahead (an absent or occupied binding site), the trailing head remains anchored upon the filament while the leading head remains unbound. Leading head binding may thus induce trailing head dissociation, which is similar to proposed mechanisms for kinesin (Hancock and Howard, 1999). However, uninteresting phenomena, for instance motors moving off the actin filament end and then adhering nonspecifically to the surface substrate, could also underlie observed accumulation. Figure reproduced, with permission, from Sakamoto et al., 2000.
