Fig. 7. Model of DIDS effects. A. Scheme of a KCNQ1 and a KCNQ1/KCNE1 channel composed of four subunits with and without KCNE1 in yellow. VS = voltage sensing domain, PD = pore domain. Orange arrows indicate interactions of the voltage sensors with the pore domains. The about position of KCNE1 transmembrane segment is depicted in yellow. B Scheme of pore domain composed of two opposing KCNQ1 channel subunits with and without KCNE1. The region on the S6-segments suspected to be involved in deactivation kinetics is colored red. The PAG motif of the gate and the selectivity filter are labeled PAG and SF, respectively. C. Effect of DIDS on a simplified basic KCNQ1/KCNE1 gating scheme. DIDS shifts the balance towards open states. D. Model of KCNQ1/KCNE1. Key residues suspected to affect the mechanism of action of DIDS on channel deactivation kinetics are highlighted in red (dark blue respectively). Residues that significantly alter DIDS sensitivity if mutated are colored dark blue, residues located on the neighboring subunit which are supposed to interact with key residues are colored in green.