Ca2+ titration of NaV1. 2 (1777-1882) (panel
A) and NaV1.5 (1773-1878) (panel B). The plots show
joint 1H,15N chemical shift deviations from resonance
assignments in 0 mm Ca2+. The titration was performed by
serial addition of Ca2+ obtaining the following concentrations: 0
(red), 0.1 (orange), 0.5 (maroon), 1.5
(magenta), 2.5 (cyan), 3.5 (blue), and 4.5
mm (green) for NaV1.2 (panel A) and (0
(red), 0.1 (orange), 0.5 (maroon), 2.5
(magenta), 3.5 (cyan), 4.5 (blue), and 5.5
mm (green) for NaV1.5. Insets show
resonances Phe-1812—Ile-1813 and Phe-1808—Ile-1809 for
NaV1.2 and NaV1.5, respectively. Titration curves are
shown in supplemental Fig. S2. In panel C the joint
1H,15N chemical shift changes for NaV1.2
(1777-1882) at 4.5 mm Ca2+ are mapped onto the lowest
energy structure, interpolated between 0 ppm (blue) and 0.1 ppm
(red).