TABLE I.
Cysteine Modification Rates
| MTSMT | MTSEA | MTSES | MTSET | |
|---|---|---|---|---|
| S357C | 1,717 ± 74 −50 mV, (3) |
38 ± 9 −50 mV,(3) |
||
| A359C | 1,016 ± 25 −50 mV, (3) |
153 ± 30 −50 mV, (3) |
98 ± 27 −50 mV, (4) |
2,884 ± 518 −50 mV, (4) |
| R362C | 753 ± 309 0 mV, (3) |
614 ± 160 0 mV, (3) |
208 ± 55 0 mV, (3) |
|
| V363C | 1,537 ± 139 −50 mV, (4) |
877 ± 121 0 mV, (3) |
NR | |
| I364C | 601 ± 94 −50 mV, (3) |
4,123 ± 720 0 mV, (3) |
46 ± 22 −50 mV, (3) |
|
| R365C | 4,410 ± 242 0 mV, (3) |
20,949 ± 2,612 0 mV, (5) |
1,784 ± 600 0 mV, (3) |
|
| L366C | 2,055 ± 534 0 mV, (3) |
4,464 ± 847 0 mV (3) |
NR |
Modification rates of conducting mutants of Shaker by methanethiosulfonate reagents. Rates (M−1s−1) were calculated from the single exponential time course of changes of current amplitudes due to shifts in conductance-voltage (G-V) relationships induced by modification (Larsson et al., 1996). The voltage at which the rate was measured is indicated for each residue and MTS reagent with the number of cells examined in parentheses. The indicated voltages are identical to those used for modification of the non-conducting mutants in the corresponding experiments throughout the study. NR indicates that modification rate was too low to be measured.