Summary of steady-state kinetic parameters of NM-2A, -2B, -2C1 and myosin-7A activated by actin isoforms.

*The second order rate constant kcat/Kapp,actin (µM−1 s−1) indicates the coupling efficiency and was obtained from the initial slope of the steady-state ATPase activity versus actin concentration plot.
**Activities of NM-2C1 isoforms in the presence of 100 µM F-actin. With regard to kcat, p-values of unpaired t-tests were ≤0.01 for the combinations α- and β-/γ-actin for all NM-2 isoforms and myosin-7A.
The kcat-values for β- and γ-actin were different for NM-2C1 (p = 0.025) and myosin-7A (p = 0.005). No significant differences were found for Kapp,actin (p≥0.25 for all combinations). Coupling efficiencies differ significantly (p≤0.05) between α-actin and cytoplasmic actins for all myosin isoforms shown in the table. The coupling efficiencies of β- and γ-actin were different for myosin-7A (p<0.001).