Molecular Determinant for Specific Ca/Ba Selectivity Profiles of Low and High Threshold Ca2+ Channels -- Data Supplement - JGP--Cens et al. -- The Journal of General Physiology

TABLE S3. The Mutations at the DCS Locus Marginally Affect the Inactivation Parameters

	Ba²⁺			Ca²⁺
Mutants channel	V_in	k_in	R_in	V_in	k_in	R_in
	mV	mV	%	mV	mV	%
Ca_V2.3 WT [14]	-22 ± 1	8.5 ± 0.3	53 ± 4	-11 ± 1	8.9 ± 0.5	56 ± 3
Ca_V2.3(DSED) [7]	-22 ± 2	8.5 ± 0.8	60 ± 3	-14 ± 1	7.2 ± 0.5^a	55 ± 6
Ca_V2.3(TSQN) [22]	-21 ± 1	8.8 ± 0.4	58 ± 3	-20 ± 1^a	9.6 ± 0.5	62 ± 6
Ca_V2.3(DEEE) [11]	-20 ± 1	8.7 ± 0.9	56 ± 3	-14 ± 1	8.2 ± 1.0	59 ± 3
Ca_V2.3(DEQN) [11]	-16 ± 3^a	9.4 ± 0.8	59 ± 4	-12 ± 5	9.4 ± 1.5	62 ± 7
Ca_V2.3(GGGG) [5]	-25 ± 1	10.2 ± 0.6^a	47 ± 4	-15 ± 5	10.7 ± 1.1	47 ± 3
Ca_V2.3(AAAA) [5]	-28 ± 2^a	9.3 ± 0.6	38 ± 3^a	-20 ± 1^a	10.4 ± 1.1	49 ± 4
Ca_V2.1 WT [13]	-11 ± 1	5.7 ± 0.4	58 ± 2	-4 ± 1	3.9 ± 0.5	64 ± 4
Ca_V2.1(TEQE) [8]	-7 ± 2	7.9 ± 0.6	34 ± 3^a	-7 ± 3	6.2 ± 1.9	45 ± 7
Isochronal steady-state inactivation curves (2.5 s of conditioning voltage followed by a 400-ms test pulse to +10 mV) were fitted using the following equation: I/Imax = R_in + (1 - R_in)/(1 + exp((V - V_in)/k)), where I is the current amplitude measured during the test pulse at +10 mV for conditioning voltages varying from -80 to +50 mV, Imax is the current amplitude measured during the test pulse for a conditioning voltage to -80 mV, V_in is the potential for half inactivation, V is the voltage, k_in is the slope factor, and R_in is the proportion of noninactivating current. ^aStudentÕs t test has been used to compare each mutant value with the control Ca_V2.3, and differences were considered statistically significant when P < 0.05.