Effects of R282W HCM mutant on phosphorylation-modulated binding to actin–Tm at submaximal phosphorylation by PKA. Effects of HCM mutant R282W on C0–C2 phosphorylation were tested over a range (0–5 ng PKA/µg C0–C2) of PKA levels. WT and R282W effects on IAEDANS–actin–Tm lifetime change (percent decrease) as a function of PKA concentration. At intermediate phosphorylation levels (0.5 and 1.5 ng PKA/µM C0–C2), binding to actin or actin–Tm detected by TR-F is significantly increased in R282W (*, P < 0.003). Data are provided as mean ± SE (n > 4).