FIGURE 1.

Topology of the KCNQ1 G229D mutation. (top) Ventricular cell model together with the ionic channels (blue rectangles), pumps (green circles), and exchangers (yellow circles). I_Na is the rapid inward Na⁺ current, I_Na,b is the background Na⁺ current, I_Ca,L is the L- type Ca²⁺ current, I_Na,Ca is the Na⁺-Ca²⁺ exchanger current, I_p,Ca is the Ca²⁺ pump current, I_Ca,b is the background Ca²⁺ current, I_leak is the current of Ca²⁺ release from the sarcoplasmic reticulum (SR), I_up is the SR Ca²⁺ uptake current, I_rel is the Ca²⁺-induced Ca²⁺release, I_Kr is the rapid delayed rectifier K⁺ current, I_K1 is the inward rectifier K⁺ current, Ito is the transient outward K⁺ current, I_Ks is the slow delayed rectifier K⁺ current, I_Na,K is the Na⁺-K⁺ pump current, and I_p,K is the K ⁺ pump current. (bottom) Location of the G229D mutation within the transmembrane topology of the KCNQ1 (blue) assembly with KCNE1 (purple), which comprise the I_Ks channel. S1 to S6 are the transmembrane segments of the α-subunit in KCNQ1; E1 is the transmembrane domain of the ^®-subunit in KCNE1