A detailed atomic structure for<unk>  based on X-ray crystallography is not yet available, but structures have recently been solved by electron microscopy. In the laboratory the heterologously expressed<unk>  potassium channel comprises 4 identical alpha subunits, which form the channel's pore through the plasma membrane. Each<unk>  subunit consists of 6 transmembrane alpha helices, numbered S1-S6, a pore helix situated between S5 and S6, and cytoplasmically located N- and C-termini. The S4 helix contains a positively charged arginine or lysine amino acid residue at every 3rd position and is thought to act as a voltage-sensitive sensor, which allows the channel to respond to voltage changes by changing conformations between conducting and non-conducting states (called 'gating'). Between the S5 and S6 helices, there is an extracellular loop (known as 'the turret') and 'the pore loop', which begins and ends extracellularly but loops into the plasma membrane; the pore loop for each of the<unk>  subunits in one channel faces into the ion-conducting pore and is adjacent to the corresponding loops of the 3 other subunits, and together they form the selectivity filter region of the channel pore. The selectivity sequence, SVGFG, is very similar to that contained in bacterial KcsA channels. Although a full crystal structure for<unk>  is not yet available, a structure has been found for the cytoplasmic N-terminus, which was shown to contain a PAS domain (aminoacid 26–135) that slows the rate of deactivation.
HERG
MCN
HER2/neu
MECACAR
AEMT-CC
EPERC
BIM-1
CoWIN