Table I.

Summary of results of Boltzmann fits to the QVs and GVs of the mutant channels

MutationQV90/ON (W434F)QVOFF (W434F)QV0 (W434F)W434F (n)GV (A359C)FV90 (A359C)FV0 (A359C)A359C (n)
V1/2dVV1/2dVV1/2dVV1/2dVV1/2dVV1/2dV
mVmVmVmVmVmVmVmVmVmVmVmV
ShakerIR−49.2 ± 0.78.5 ± 0.4−53.0 ± 0.57.6 ± 0.3−74.4 ± 0.59.0 ± 0.122−22.5 ± 0.26.3 ± 0.4−47.1 ± 0.514.6 ± 0.6−115.3 ± 9.214.9 ± 0.411
I384N−68.5 ± 0.68.0 ± 0.3−69.8 ± 0.38.3 ± 0.3−69.2 ± 0.27.9 ± 0.210−71.6 ± 1.110.7 ± 0.8−72.5.4 ± 0.813.4 ± 0.18
F484G−67.7 ± 0.68.0 ± 0.2−68.0 ± 0.48.0 ± 0.3−71.6 ± 0.37.1 ± 0.26−70.3 ± 0.710.6 ± 0.2−70.9 ± 1.114.3 ± 0.65
Y485A−48.5 ± 0.410.9 ± 0.3−49.1 ± 0.211.6 ± 0.2−55.1 ± 0.813.4 ± 0.75
I384A*−34.6 ± 0.113.2 ± 0.9−36.6 ± 0.115.2 ± 1.0−106.5 ± 0.49.0 ± 0.34−32.6 ± 0.26.6 ± 0.26
I384A−37.8 ± 0.412.9 ± 0.4−106.5 ± 0.49.0 ± 0.35−34.7 ± 0.46.6 ± 0.2−39.2 ± 1.211.3 ± 1.4−145 ± 5.411.3 ± 1.26
F484A−58.5 ± 0.58.5 ± 0.3−61.0 ± 0.611.7 ± 0.5−63.8 ± 0.29.4 ± 0.45−29.2 ± 0.68.3 ± 0.65
I384C*−48.9 ± 0.511.5 ± 0.9−53.0 ± 0.413.6 ± 0.7−114.3 ± 0.89.3 ± 0.34−37.9 ± 0.67.5 ± 0.44
  • V1/2, ± SD, and dV (see Materials and methods) of single Boltzmann fits of QV90, QVOFF, QV0, GV, FV90, and FV0 are given for ShakerIR wild type and the mutants I384N, F484G, Y485A, I384A, F484A, and I384C. The secondary mutation (W434F or A359C) is given on top of each column. The GV and QV90 values (QVON and QVOFF) of I384A* and I384C* are obtained from holding potentials of Vhold = −140 mV and −120 mV, respectively, because of the strongly shifted QVOFF. QV90 and QV140 of I384A are not significantly displaced with respect to one another. The n given in the table indicates the number of fully independent measurements (different batch of oocytes). All blank cells indicate that the data have not been determined.