Table I.
Summary of cysteine point–mutated Shaker channels showing MTS-induced G-V shifts and DHA sensitivity before and after MTS modification
| Channel | 10% level | ΔVDHA | p | ΔVMTSEA+ | p | ΔVDHA(MTSEA+) | −ΔΔVDHA | p | ΔVMTSES− | p | ΔVDHA(MTSES−) | −ΔΔVDHA | p |
| mV | mV | mV | mV | mV | mV | mV | mV | ||||||
| WT-IR | −35.4 ± 0.7 (8) | −4.4 ± 0.9 (5) | −1.0 ± 1.0 (4) | 0.4 | −4.5 ± 0.6 (4) | −0.1 | >0.05 | ||||||
| S3–S4 | |||||||||||||
| I325C | −34.8 ± 1.3 (10) | −1.1 ± 1.4 (5) | <0.05 | +19.2 ± 1.1 (5) | <0.0001 | −5.9 ± 0.5 (5) | +4.8 | <0.001 | |||||
| L327C | −31.4 ± 0.4 (6) | −4.3 ± 0.6 (3) | >0.05 | +7.0 ± 0.8 (3) | 0.01 | −5.1 ± 0.5 (3) | +0.8 | >0.05 | |||||
| T329C | −49.8 ± 0.6 (17) | −0.4 ± 0.6 (8) | <0.01 | +11.9 ± 0.4 (7) | <0.0001 | −3.3 ± 0.3 (7) | +2.8 | <0.05 | |||||
| E333C | −40.0 ± 0.8 (16) | −2.9 ± 0.5 (6) | >0.05 | +1.5 ± 0.8 (7) | 0.1 | −2.6 ± 0.5 (7) | −0.3 | >0.05 | −4.0 ± 0.5 (3) | 0.01 | −4.3 ± 0.3 (3) | +1.4 | >0.05 |
| S357C | −30.0 ± 1.4 (12) | −5.3 ± 0.7 (4) | >0.05 | −21.7 ± 2.1 (4) | 0.002 | −3.3 ± 0.6 (4) | −2.0 | >0.05 | |||||
| A359C | −35.6 ± 0.6 (21) | −2.8 ± 0.5 (5) | >0.05 | +18.8 ± 2.0 (6) | 0.0002 | −7.3 ± 0.9 (6) | +4.5 | <0.001 | |||||
| I360C | −30.2 ± 1.3 (9) | −1.5 ± 0.4 (4) | >0.05 | +6.8 ± 0.9 (5) | 0.002 | −8.5 ± 1.5 (5) | +7.0 | <0.001 | |||||
| V363C | −38.8 ± 0.4 (8) | −3.4 ± 0.4 (4) | >0.05 | +1.8 ± 0.4 (4) | 0.02 | −3.1 ± 0.5 (4) | −0.3 | >0.05 | |||||
| I364C | −47.5 ± 0.6 (12) | −3.9 ± 0.5 (5) | >0.05 | +0.6 ± 0.3 (5) | 0.1 | −3.5 ± 0.3 (5) | −0.4 | >0.05 | 1.6 ± 1.1 (3) | 0.3 | −2.0 ± 0.8 (3) | −2.0 | >0.05 |
| L366C | −50.0 ± 1.0 (19) | −7.7 ± 1.7 (7) | <0.05 | −2.0 ± 1.4 (5) | 0.2 | −4.5 ± 0.3 (5) | −3.2 | <0.05 | −0.4 ± 0.5 (6) | 0.5 | −4.1 ± 0.8 (6) | −3.5 | <0.01 |
| V367C | −53.5 ±0.8 (18) | −3.1 ± 0.2 (5) | >0.05 | −3.9 ± 2.5 (9) | 0.2 | −3.9 ± 0.5 (9) | +0.8 | >0.05 | +0.4 ± 0.1 (4) | 0.04 | −4.0 ± 0.5 (4) | +0.9 | >0.05 |
| S5–S6 | |||||||||||||
| F416C | −39.4 ± 0.7 (19) | −3.5 ± 0.7 (7) | >0.05 | +26.9 ± 0.6 (8) | <0.0001 | −4.4 ± 0.9 (5) | +0.9 | >0.05 | +3.7 ± 0.3 (4) | 0.002 | |||
| A417C | −34.7 ± 0.8 (10) | −4.3 ± 0.4 (5) | >0.05 | −1.4 ± 0.5 (5) | 0.04 | −4.2 ± 0.1 (5) | −0.1 | >0.05 | |||||
| G420C | −32.1 ± 0.9 (16) | −3.2 ± 0.4 (5) | >0.05 | +1.5 ± 1.3 (7) | 0.3 | −4.8 ± 0.9 (7) | +1.6 | >0.05 | −0.7 ± 0.4 (5) | 0.2 | −4.8 ± 0.2 (5) | +1.5 | >0.05 |
| S421C | −34.7 ± 0.5 (23) | −4.2 ± 0.2 (6) | >0.05 | +2.9 ± 0.6 (8) | 0.001 | −6.2 ± 0.6 (8) | +2.1 | >0.05 | |||||
| G452C | −39.0 ± 1.2 (11) | −3.9 ± 0.3 (5) | >0.05 | +5.4 ± 0.8 (6) | 0.0008 | −6.0 ± 0.6 (6) | +2.1 | >0.05 | |||||
| V453C | −38.8 ± 1.4 (12) | −4.4 ± 0.5 (6) | >0.05 | +5.2 ± 0.8 (6) | 0.002 | −5.4 ± 0.3 (5) | +1.0 | >0.05 | |||||
70 µM DHA, 100 µM MTSEA+, and 1 M MTSES− were used. Data are expressed as mean ± SEM, with n denoted in parenthesis. Underlined data mark mutants with altered DHA sensitivity compared to WT-IR. Statistically significant MTS-induced ΔV or ΔΔVDHA are in bold.