Deoxy-ATP (dATP) impact on IHM/SRX motors. The SRX inhibitor, dATP, was exchanged for ATP in the motility assay with the WT and E525K 2HEP and 15HEP constructs at 100% myosin surface occupancy. Data are normalized to the respective (i.e., WT and E525K) 2HEP mean Velocity Index data in the presence of ATP. * identifies significantly different than control (P = 0.01). Data points represent mean values ± SD of three experiments from separate protein preparations.