Ion channels that are selective for potassium ions. They are tetrameric, with hybrid combinations of subunits possible in some cases. More than 80 genes encode components of these channels and even more are involved in regulating their activity. There are four main classes: 1. Calcium-activated channels (BK and SK subtypes). 2. Inwardly-rectifying channels (ROMK (Kir1.1), G-protein-coupled receptor-regulated (GIRKs, Kir3.x), and ATP-sensitive (Kir6.x, associated with sulphonyl urea receptors). 3. Tandem-pore domain channels (TWI, TRAAK, TREK and TASK). 4. Voltage-gated channels (hERG, (Kv11.1); KvLQT1 (Kv7.1). See A-type channels; delayed rectifier channels; DLGs; minK; shaker; weaver. Disorders of potassium channels are associated with Andersen's syndrome, Bartter's syndrome, episodic ataxia-1, hyperinsulinism, Jervell and Lange-Nielsen syndrome, long QT syndrome, nesidioblastosis, neuronal ceroid lipofuscinosis-6, short QT syndrome, and spinocerebellar ataxia-13. Toxins that act on potassium channels include agitoxin, apamin, charybdotoxin, iberiotoxin, margaratoxin, noxiustoxin, scyllatoxin, SGTx1, and ShK toxin.
Subjects: Chemistry — Medicine and Health.