Fig. 5.
A: velocity of actin propulsion by myosin (νmax) when 1) myosin is phosphorylated in the presence of caffeine (or vehicle) (i.e., prior to introduction onto the motility surface; ○) and 2) caffeine (or vehicle) is added to the already thiophosphorylated myosin as well as the final assay buffer containing ATP, to ensure that the caffeine is not flushed out of the motility assay during velocity measurements (▲); n = 3 for both assays. B: number of actin filaments bound to the motility surface when caffeine (or vehicle) was added to the thiophosphorylated myosin, the labeled actin, and the actin buffer used to wash away the unattached actin filaments (no ATP was present in these conditions); n = 5.