Potassium delayed rectifier channels are a sub-type of potassium channels found in various species of animals. They are responsible for the late-repolarization phase and the duration of action potential, especially in cardiac myocytes.

There are two types of delayed rectifier channels (I_k). The Fast component is known as I_kr and is encoded by the gene KCNH2 in Xenopus. This channel’s α-subunit is a 6-transmembrane domains voltage dependent potassium channel and its regulatory β-subunit, MiRP1, is required to reconstitute native Ikr¹.

KCNE1 and KCNQ1 are the genes encoding the two components of the I_ks channel and this association was not fully understood for a long time. KCNQ1 (K_V7.1) is a protein with six transmembrane domains and a typical pore loop containing a potassium signature sequence.

The KNCE1 gene encodes the protein “minK”. This gene is one of family of genes that encode small channel subunits (smaller than 130 amino-acids) that co-assemble with bigger subunits thus changing channel gating properties. These are currently the smallest known potassium channel subunits. Their small size and putative transmembrane domain prevent them from forming channels on their own.  In addition, in an experiment where mammalian cells were transfected with minK, no K⁺ currents were observed. When transfecting cells with a combination of KNCE1 and KNCQ1 the currents observed were up to ten times larger than currents induced by the KNCQ1 subunit alone².

The loss of function of I_ks is tightly linked with the long QT syndrome and bilateral deafness and gain of function was found to be linked with cardiac tachy-arrhythmias^3,4.