Figure 3. Effect of disease-related protein modifications on the Ca²⁺ binding sensitivity of the thin filament.

Panel A shows the Ca²⁺ dependent increases in IAANS fluorescence for thin filament bound control (□), and the DCM mutants, TnI K36Q (), TnT R131W (○), TnT R141W (•), TnT R205L (▪) and TnT ΔK210 (⋆) as a function of pCa. Panel B shows the Ca²⁺ dependent increases in IAANS fluorescence for thin filament bound control (□), and the HCM mutants, TnT R92Q (▾) and TnI S166F (▴) as a function of pCa. Panel C shows the Ca²⁺ dependent increases in IAANS fluorescence for thin filament bound control (□), and the RCM mutants, TnI D190H (▽) and TnI R192H (▵) as a function of pCa. Panel D shows the Ca²⁺ dependent increases in IAANS fluorescence for thin filament bound control (□) and ischemic related truncated TnI (1-192) () as a function of pCa. The data sets were normalized individually for each mutant. All complexes consist of the full length Tn subunits of , TnI and TnT, except for ischemic related truncated TnI (1-192). The disease related modification is either in TnI or TnT, in either case, the other protein (TnT or TnI) was wild type. The Ca²⁺ sensitivities were reported as a dissociation constant K_d, representing a mean of three to four separate titrations ± S.E.M.