CALM3 and familial long QT syndrome: At saturating Ca2+ concentrations (1 mm CaCl2), 1H‐15N HSQC NMR spectral overlays showed incomplete homology with the distribution of CaM‐WT signals, indicating that LQTS‐associated variants proteins adopt alternative conformations when bound to Kv7.1‐HB507‐536 (Fig. 11B).