Figure 6.

Mavacamten populates myosin in the SRX state more effectively in STFs than in HMM and S1. Comparison of the responses of mavacamten between BcS1, BcHMM, and BcSTFs for (A) A_slow and (B) k_fast. BcS1 refers to bovine cardiac myosin subfragment-1, BcHMM refers to bovine cardiac heavy meromyosin, and BcSTFs refers to bovine cardiac synthetic thick filaments. Data are expressed as the mean ± SEM (n = 12 from three experiments). In panels A and B, concentrations of mavacamten required for a half-maximal increase in A_slow (EC₅₀) for BcSTFs, BcHMM, and BcS1 were 0.66 ± 0.05, 1.17 ± 0.13, and 2.16 ± 0.19 μM, whereas those required for the half-maximal decrease (IC₅₀) in k_fast were 0.31 ± 0.05, 0.54 ± 0.08, and 0.67 ± 0.09 μM, respectively. SRX, super-relaxed.