CACNA1C and familial long QT syndrome: LQTS-associated CaM variant D133H alters binding affinities to Cav1.2 CaMBDs. ITC was used to assess the binding affinities and thermodynamic parameters of CaM-WT and D133H to Cav1.2-IQ1665−1685 and Cav1.2-NSCaTE51−67 domains (Figure 8).