Myo4p–She3p moves processively when bound to tetrameric She2p. (A) Diagram of the experimental setup for the TIRF processivity assay. The motor complex is tracked by the YFP tag on She2p. The yellow stars represent YFP. TM, tropomyosin. (B) Myo4p–She3p bound to She2p-YFP (green) moves processively on yeast actin–tropomyosin (Tpm1p) filament (red) in 1 mM MgATP. Yellow arrowheads indicate the moving YFP particle. (C) Representative run length histogram at 1 mM Mg ATP on yeast actin–tropomyosin. A total of 67 processive runs was observed (n = 3).