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jce12178-sup-0001-supmat.doc26KSupporting Material

Figure S1. Activation kinetics of WT- and mutant V307L-IKs. (A) Voltage dependence of activation of WT- (n=9-27) and V307L-IKs (n=3–7). Rate of activation was determined by measuring time to half maximal current. Representative current traces illustrating IKs activation at +40 mV in CHO-K1 cells expressing (B) WT- or (C) V307L-KCNQ1. Current traces were normalized to same peak current amplitude.

Figure S2. Representative recordings of time courses of activation of (A) WT- and (B) N588K-IKr. Activation kinetic was measured by using the envelope of tails protocol displayed in the inset: from a holding potential (HP) of −80 mV the cell was depolarized to +40 mV test pulse (TP) for variable duration from 50 milliseconds to 790 milliseconds (50-millisecond increments) before depolarization to −60 mV for 1 second to observe the tail current. (C) The tail current plotted as function of time. Mean average data were fitted with a single exponential function to obtain time constants for activation. All values are presented as mean ± SEM. *P<0.05, **P<0.01.

jce12178-sup-0003-figuresS3.tif504KFigure S3. Fully activated I–V relation of WT- and N588K-IKr. Representative whole-cell current traces recorded from HEK-293T cells transfected with (A) WT- (n=39) or (B) N588K-KCNH2 (n=21) using the voltage protocol in the inset: cells were held at −80 mV and membrane currents were evoked by a double pulse protocol. After a 500-millisecond initial depolarizing voltage step (every 10 seconds) to +40 mV, the cell was repolarized to voltages between −120 mV and +40 mV (20 mV increments) for 500 milliseconds. (C) I–V curve for the peak IKr tail plotted as a function of test potentials.
jce12178-sup-0004-figuresS4.tif653KFigure S4. Representative current traces of (A) WT- and (B) N588K-IKr depicting differences in inactivation. Voltage protocol is shown in the inset: After an initial long depolarizing pulse (2 seconds) to +40 mV from a holding potential (HP) of −80 mV, a brief (2-millisecond) hyperpolarization step to −100 mV was applied to elicit rapid recovery from inactivation followed by a second depolarizing pulse (2 seconds) to +40 mV to observe “reinactivation.” (C) Bar graph representing inactivated fraction of end-pulse WT- and N588K-IKr at +40 mV. Data are presented as mean ± SEM. *P<0.05, **P<0.01.

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