ROLE OF POTASSIUM CHANNELS IN NEUROLOGICAL DISORDERS

Abstract

Potassium channels (K) are a diverse and ubiquitous family of membrane proteins present in both excitable and nonexcitable cells. Members of this channel family play critical roles in cellular signaling processes, regulating neurotransmitter release, heart rate, insulin secretion, neuronal excitability, epithelial electrolyte transport, smooth muscle contraction, and cell volume regulation. Precise biophysical properties, subunit stoichiometry, channel assembly and modulation by second messenger and ligands have been addressed. Potassium channels (K) conduct ions across the cell membrane down the electrochemical gradient for potassium. They contain a K‏ channel signature sequence form the selectivity filter, they either ligand gated or voltage gated which include;voltage-gated,Ca2+ activated, Na+ activated and inward rectifiers K channels. Structurally potassium channels are classified into three groups; six transmembrane domains TMD one pore group (voltage-gated and Ca2+-activated K channels), two TMDone pore (inward rectifier K+ channels) and four TMD two pore (“leak” K channels; TWIK, TREK, TRAAK and TASK).Each of these groups is further divided into families, which in turn are divided into subfamilies, with several closely related members within most of these subfamilies. The first Kv channel was cloned from the Shaker mutant of Drosophila melanogaster in 1987. The human ortholog of Shaker Kchannels is encoded by the gene KCNA1 (Kv1.1). Since the first cloning, several other genes encoding for Kv channels have been identified from many different species. Based on sequence relatedness, Kv channels have been classified in subfamilies by using the abbreviation Kvy.x.