TABLE 2.

Biophysical properties of CEEE mutants

With α2bδ in 10 Ba2+	Inactivation (5 s) E0.5 (mV)		Activation E0.5 (mV)		Peak IBa (μA)
		−β	+β3	−β	+β3	−β	+β3
CEEE	−17 ± 1 (3) z = 2.6	−19 ± 1 (13) z = 2.6	−4 ± 1 (6) z = 4.1± 0.3	−7 ± 0.5 (23) z = 4.4 ± 0.2	−0.39 ± 0.02 (6)	−1.9 ± 0.2 (23)
CEEE + E462R	−32.2 ± 0.4 mV (16) z = 2.8	−35 ± 1 (17) z = 3.1	−7 ± 1 (12) z = 4.0 ± 0.5	−9 ± 1 (18) z = 4.0 ± 0.3	−1.4 ± 0.2 (7)	−2.1 ± 0.4 (13)
CEEE + E462K	−19 ± 1 (4) z = 2.2	−28 ± 1 (10) z = 2.5	−4 ± 1 (6) z = 4.0 ± 0.2	−10 ± 1 (14) z = 4.3 ± 0.3	−0.6 ± 0.5 (6)	−1.5 ± 0.2 (14)
CEEE + Q473K	n.d.	−23 ± 1 (8) z = 3.1	n.d.	−12 ± 1 (5) z = 4.7 ± 0.5	n.d.	−1.9 ± 0.5 (5)
CEEE + E462R + Q473K	−25 ± 1 (5) z = 2.6	−30 ± 1 (8) z = 2.9	−3 ± 1 (6) z = 4.0 ± 0.3	−6 ± 1 (7) z = 3.7 ± 0.2	−1.1 ± 0.1 (6)	−0.8 ± 0.1 (7)

Biophysical parameters of the CEEE chimera and its derivative mutant channels expressed in Xenopus oocytes in the presence of Ca_Vα2bδ and Ca_Vβ3 subunits. Whole-cell currents were measured in 10 mM Ba²⁺ throughout. The voltage dependence of inactivation was determined from the peak currents measured at 0 mV after 5 s pulses from −100 to +50 mV. Relative currents were fitted to Boltzmann Eq. 1. Activation data were estimated from the mean I/V relationships and fitted to Boltzmann Eq. 2. Peak I_Ba was determined from I/V relationships for the corresponding experiments. The data are shown with the mean ± SE and the number n of samples appears in parentheses.

n.d., not determined.