Representative displacement trajectory of SMM filament moving on stationary actin filament. Fluorescence of 605 nm QD on RLC (black trace) and 705 nm QD on LMM (red trace) incorporated into RLC-LMM cofilament was simultaneously acquired, tracked, and reoriented along the axis of motion. [ATP] = 10 µM. (A and B) Insets reveal dwells (horizontal lines) followed by jumps (vertical lines) in the RLC trace. The LMM traces were translated from the RLC traces by −80 nm in the insets for better comparison.