TABLE 1.

Binding parameters for wild-type and mutant Ca²⁺ channels.

	KDHP (pM)	KCaC (%M)	%
Wild-type	367 ± 19	0.322 ± 0.055	0.48 ± 0.05
Mut A	1660 ± 120 *	0.344 ± 0.065	~1 *
Mut B	391 ± 52	0.216 ± 0.024	0.45 ± 0.05
Mut C	460 ± 50	n.d.	n.d.
E1122A	294 ± 42	1.14 ± 0.20 *	n.d.
D1127A	511 ± 53	1.61 ± 0.94 *	0.75 ± 0.07 *
D1129A	289 ± 80	21.0 ± 6.0 *	n.d.

K_DHP values were determined by [³H]-PN200-110 binding in the absence of calcicludine, as described in Fig. 2. K_CaC values were determined using whole-cell patch-clamp electrophysiology, as described in Figs 4–5. Values for the cooperativity factor alpha (α) for wild-type, Mut A and Mut B were determined by fitting the data depicted in Fig. 3. Mut C proved to be insensitive to calcicludine, so K_CaC and α for this mutant were “not determined” (n.d.). Binding data from E1122A and D1129A were fit using the mutants’ respective K_DHP and K_CaC values and a value for α equal to that of wild-type (i.e., 0.48). In contrast to E1122A and D1129A, it was necessary to adjust α to 0.75 to achieve a reasonable fit for D1127A.

^*; P<0.05.