Two potassium currents, IKs and IKr, provide the principal repolarising currents in cardiac myocytes for the termination of action potentials. Potassium voltage-gated channel subfamily KQT member 1 (KCNQ1 aka Kv7.1) is the pore-forming alpha subunit of a complex also containing an ancillary protein from potassium voltage-gated channel subfamily E members (KCNE) that assemble as a beta subunit. The stoichiometry is believed to be 4 KCNQ1 subunits to 2 KCNE subunits (Plant et al. 2014). A-kinase anchor protein 9 (AKAP9) is an essential anchoring protein that binds to KCNQ1. Defects in KCNQ1 that disrupt this binding can result in type 1 long-QT syndrome (LQT1), a hereditary, potentially lethal arrhythmia syndrome (Chen et al. 2007). The AKAP9:KCNQ1:KCNE complex creates the slowly activating delayed rectifier cardiac potassium current IKs by the efflux of K+ from cardiac cells (Schroeder et al. 2000).
Tester, DJ, Sampson, KJ, Chen, L, Kass, RS, Marquardt, ML, Ackerman, MJ
Goldstein, SA, Dai, H, Xiong, D, Plant, LD
Greger, R, Jentsch, TJ, Bleich, M, Schroeder, BC, Warth, R, Fehr, S, Waldegger, S
delayed rectifier potassium channel activity of AKAP9:KCNQ1 tetramer:KCNE dimer [plasma membrane]
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