[1] Transmembrane channels are also found in the membranes of organelles including the nucleus, the endoplasmic reticulum, the Golgi apparatus, mitochondria, chloroplasts, and lysosomes.
Some channels are less selective than typical transporters and pumps, differentiating solutes primarily by size and ionic charge.
Using X-ray diffraction data and atomic model computations a likely structure of the channel consists of a number of protein alpha-helixes forming an hourglass shaped pore with the narrowest point halfway through the membrane's lipid bilayer.
To move through the channel the potassium ions must shed their aqueous matrix and enter a selectivity filter composed of carbonyl oxygens.
Additional disorders resulting from malfunctions in ion channels include forms of epilepsy, cardiac arrhythmia, certain types of periodic paralysis and ataxia.