Drosophila myosin mutants model the disparate severity of type 1 and type 2B distal arthrogryposis and indicate an enhanced actin affinity mechanism

Table 4 ATPase and in vitro motility values for DA1 (F437I) myosin

Myosin isoform (n for ATPase/motility)	Basal Mg-ATPase (s^-1)	Actin-stimulated V_max (s^-1)	Actin-stimulated K_m (μM)	Catalytic efficiency (s^-1/μM)	Motility (μm/s)
pwMhc2-control (6/8)	0.228 ± 0.039	1.682 ± 0.365	0.692 ± 0.154	2.506 ± 0.685	7.11 ± 0.72
F437I-DA1 (6/7)	0.071 ± 0.047 ***	0.190 ± 0.054 ****	0.562 ± 0.222	0.429 ± 0.309 ***	3.19 ± 0.48****

For ATPase assays, two technical replicates were averaged to obtain the values for each biological replicate (n value). For in vitro motility, mean values of at least 30 motile filaments are included for each biological replicate (n value). Standard deviations are indicated for each mean. Statistical significance was determined using Student’s t test. Significant differences were assumed for P < 0.05 (*** = P < 0.001, **** = P < 0.0001)

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