TABLE 1.
Biophysical parameters of CaV3.2 wild-type and S6 mutant channels were estimated from recordings obtained with the cut-open oocyte technique in the presence of 10 mm Ba2+
Activation properties (E0.5,act and z) were estimated from the mean I-V relationships and fitted to a Boltzmann equation, where z is the slope factor. Activation and inactivation energies were calculated as follows: ΔGact = z · F · E0.5,act; ΔΔGact = ΔGact,mut − ΔGact,wt; ΔGinact = z · F · E0.5,inact; and ΔΔGinact = ΔGinact,mut − ΔGinact,wt. The voltage dependence of inactivation was determined from the peak currents after 2-s depolarizing pulses from a holding potential of −120 mV. The data are shown with the mean ± S.E. of the individual experiments and the number of experiments appears in parentheses.
| E0.5, act | ΔGact | ΔΔGact | Ipeak | E0.5, inact | ΔGinact | τact, −20 mV | τinact, −20 mV | τdeact, −50 mV | |
|---|---|---|---|---|---|---|---|---|---|
| kcal mol−1 | nA | kcal mol−1 | ms | ||||||
| CaV3.2 WT | −47 ± 1 (37) | −4.3 ± 0.2 | NAa | −1300 ± 200 | −65 ± 1 (10) | −8.6 ± 0.5 | 3.2 ± 0.1 (18) | 11.6 ± 0.2 | 8.4 ± 0.6 (9) |
| V1005A | −36 ± 1 (5) | −3.3 ± 0.2 | 1.0 ± 0.4 | −160 ± 40 | −58.2 ± 0.5 (5) | −7.3 ± 0.5 | 3.5 ± 0.2 (5) | 13.3 ± 0.6b | 3.9 ± 0.9b (5) |
| V1005G | −37 ± 1 (5) | −3.0 ± 0.3b | 1.3 ± 0.5 | −170 ± 40 | −61 ± 1 (4) | −8.3 ± 0.6 | 2.62 ± 0.09 (5) | 17.2 ± 0.4c | 5 ± 1 (5) |
| L1006A | −43 ± 2 (5) | −4.5 ± 0.5 | 0.2 ± 0.7 | −210 ± 70 | −67 ± 1 (5) | −7.1 ± 0.7 | 3.0 ± 0.3 (5) | 13 ± 1 | 4 ± 1b (5) |
| L1006G | −39 ± 2 (6) | −3.8 ± 0.3 | 0.5 ± 0.5 | −300 ± 100 | −63 ± 1 (6) | −7.3 ± 0.8 | 3.3 ± 0.1 (6) | 12.5 ± 0.3 | 3.0 ± 0.9c (6) |
| F1007G | −48.6 ± 0.7 (7) | −4.7 ± 0.2 | −0.4 ± 0.4 | −140 ± 40 | −65 ± 2 (7) | −6.7 ± 0.4 | 4.3 ± 0.3c (7) | 43 ± 2c | 7.5 ± 2 (8) |
| N1008A | −35 ± 2 (4) | −3.1 ± 0.3 | 1.2 ± 0.5 | −120 ± 20 | −62 ± 1 (5) | −6.6 ± 0.4 | 3.2 ± 0.6 (4) | 8.2 ± 0.6c | 3.0 ± 0.8c (5) |
| N1008G | −38.8 ± 0.9 (5) | −3.2 ± 0.2 | 1.1 ± 0.4 | −200 ± 100 | −65 ± 1 (4) | −6.8 ± 0.5 | 2.4 ± 0.4 (5) | 7.1 ± 0.9c | 2.5 ± 0.5c (5) |
| L1009A | −39 ± 2 (11) | −3.2 ± 0.4b | 1.1 ± 0.6 | −500 ± 200 | −71 ± 3 (5) | −5.9 ± 0.4 | 5.4 ± 0.6 (7) | 16 ± 3 | 3.0 ± 0.7c (6) |
| L1009G | −44 ± 2 (6) | −3.3 ± 0.3 | 1.0 ± 0.5 | −900 ± 400 | −63 ± 1 (6) | −7.9 ± 0.6 | 3.6 ± 0.2 (6) | 15.6 ± 0.4c | 7 ± 1 (6) |
| L1010A | −26 ± 1 (5) | −1.3 ± 0.1c | 3.0 ± 0.3 | −170 ± 30 | −58 ± 3 (3) | −6.9 ± 0.4 | 4.0 ± 0.3c (5) | 16.0 ± 0.8c | 3.5 ± 0.9b (4) |
| L1010G | −34.9 ± 0.9 (9) | −2.6 ± 0.2c | 1.7 ± 0.4 | −600 ± 100 | −67.5 ± 0.7 (3) | −8.0 ± 0.3 | 4.4 ± 0.6 (9) | 10.6 ± 0.6 | 6.7 ± 0.5 (4) |
| V1011A | −45 ± 2 (6) | −4.2 ± 0.4 | 0.1 ± 0.6 | −800 ± 200 | −63 ± 2 (3) | −8.4 ± 0.4 | 4.2 ± 0.6b (6) | 28.4 ± 0.7c | 17 ± 1c (5) |
| V1011G | −50 ± 1 (9) | −5.0 ± 0.3 | −0.7 ± 0.5 | −900 ± 200 | −67 ± 1 (11) | −7.8 ± 0.4 | 5.2 ± 0.5c (11) | 115 ± 16c | 8 ± 1 (4) |
| A1012G | −41 ± 3 (5) | −3.1 ± 0.4b | 1.2 ± 0.6 | −500 ± 200 | −66.0 ± 0.4 (3) | −6.2 ± 0.4 | 3.1 ± 0.1 (5) | 15.2 ± 0.6c | 11.3 ± 0.7 (5) |
| I1013A | −41 ± 1 (10) | −3.6 ± 0.2 | 0.7 ± 0.4 | −400 ± 100 | −64 ± 2 (9) | −7.7 ± 0.6 | 4.8 ± 0.5**(10) | 55 ± 1c | 20 ± 4c (3) |
| I1013G | −54 ± 1 (10) | −5.4 ± 0.3b | −1.1 ± 0.5 | −390 ± 90 | −66.8 ± 0.7 (5) | −9 ± 1 | 8.5 ± 0.4c (10) | 68 ± 4c | 30 ± 9b (5) |
| I1013L | −41 ± 2 (5) | −3.2 ± 0.4 | 1.1 ± 0.3 | −170 ± 60 | −63.3 ± 0.7 (4) | −6.4 ± 0.1 | 3.7 ± 0.3 (5) | 18.4 ± 0.3c | 10.4 ± 0.5 (5) |
| I1013V | −45.5 ± 0.8 (7) | −4.2 ± 0.3 | 0.1 ± 0.5 | −220 ± 60 | −66 ± 1 (6) | −8.0 ± 0.3 | 2.21 ± 0.07c (7) | 18.1 ± 0.5c | 8 ± 2 (7) |
| L1014A | −39 ± 1 (6) | −3.1 ± 0.3b | 1.2 ± 0.5 | −700 ± 300 | −66 ± 2 (6) | −7.8 ± 0.6 | 5.2 ± 0.4 (6) | 17.7 ± 0.4c | 11.0 ± 0.8 (6) |
| L1014G | −38 ± 1 (5) | −3.0 ± 0.2b | 1.3 ± 0.4 | −1100 ± 500 | −67.0 ± 0.9 (5) | −9.9 ± 0.5 | 5.1 ± 0.4c (5) | 20.8 ± 0.3c | 11 ± 2 (5) |
| V1015A | −42 ± 1 (5) | −2.5 ± 0.1c | 1.8 ± 0.3 | −330 ± 50 | NDd | ND | 4.0 ± 0.3 (5) | 12 ± 1 | ND |
| V1015G | −43 ± 1 (5) | −2.7 ± 0.1b | 1.4 ± 0.3 | −330 ± 30 | −75 ± 2 (4) | −7.0 ± 0.5 | 4.9 ± 0.4c (7) | 24 ± 1c | 3.6 ± 0.8c (5) |
| E1016A | −47 ± 1 (6) | −4.0 ± 0.2 | 0.3 ± 0.4 | −400 ± 100 | −67 ± 1 (6) | −8.8 ± 0.6 | 4.1 ± 0.2c (6) | 15.9 ± 0.6c | 10.7 ± 0.5 (6) |
| E1016G | −43 ± 3 (6) | −3.1 ± 0.4b | 1.2 ± 0.6 | −160 ± 30 | ND | ND | 5.9 ± 0.5c (6) | 36 ± 3c | ND |
| N1548A | −42 ± 1 (5) | −3.9 ± 0.1 | 0.4 ± 0.3 | −400 ± 300 | −80 ± 1 (4) | −6.0 ± 0.2b | 3.4 ± 0.2 (5) | 9.5 ± 0.8c | 3 ± 1 (5) |
| N1548G | −40.2 ± 0.9 (8) | −3.9 ± 0.2 | 0.4 ± 0.4 | −400 ± 100 | −66 ± 2 (8) | −8.1 ± 0.4 | 2.6 ± 0.2 (8)c | 6.8 ± 0.8c | 2.9 ± 0.5c (10) |
| M1549A | −42 ± 2 (7) | −3.1 ± 0.2b | 1.2 ± 0.4 | −400 ± 100 | −68 ± 2 (4) | −6.2 ± 0.4 | 6.3 ± 0.5c (7) | 29 ± 2c | 11 ± 3 (5) |
| N1853A | −37 ± 1 (5) | −3.2 ± 0.3b | 1.1 ± 0.5 | −400 ± 200 | ND | ND | 5.0 ± 0.3c (5) | 14.1 ± 0.3c | ND |
| N1853G | −37 ± 3 (5) | −2.2 ± 0.3c | 2.1 ± 0.5 | −500 ± 200 | ND | ND | 3.4 ± 0.2 (5) | 11.6 ± 0.5 | ND |
a NA, not applicable.
b p < 0.01 as compared with CaV3.2 WT.
c p < 0.001 as compared with CaV3.2 WT.
d ND, not determined.