FIGURE 2.

Voltage-dependent activation and inactivation of Cav1.4 in the absence and presence of CaBP4. A, voltage protocol used for the determination of activation properties (top left) and representative family of Ca²⁺ current traces for Cav1.4 in the absence (middle left) and presence of CaBP4 (bottom left). Currents were recorded in bath solution containing 10 mm Ca²⁺ as charge carrier. Similar experiments were used for the determination of I/V relationships (panels C and D) and activation curves (Figs. 3, 4, and 6). B, voltage protocol used for the determination of pseudo-steady-state inactivation properties (top right) and representative family of Ca²⁺ current traces for Cav1.4 in the absence (middle right) and presence of CaBP4 (bottom right). Similar experiments were used for the determination of pseudo-steady-state inactivation curves (Figs. 3, 4, and 6). C, I/V relationship for Cav1.4. D, I/V relationship for Cav1.4 in the presence of CaBP4. In C and D, currents were recorded in bath solution containing 10 mm Ca²⁺ (circles) or 10 mm Ba²⁺ (squares) as charge carrier. Currents were normalized to peak Ba²⁺ current.