VOLTAGE-GATED K+ CHANNELS OF THE MAMMALIAN BRAIN

Research on voltage-gated K+ channels of the mammalian brain has seen a flood of new data in the last 2 years. A genetic approach, based on the Shaker mutation of Drosophila, led to cDNA clones for mammalian voltage-gated K+ channels. K+ channel proteins were detected independently and purified with the help of channel specific toxins. From these studies the structure of two families of mammalian K+ channels emerged. One family is defined molecularly by the sequence homology of its members, the other by binding sites for the snake toxin dendrotoxin. The two families have several members in common. The voltage-gated K+ channels of mammalian brain are oligomers of glycosilated peptides of 65-95 kDa. The primary structure of these subunits is characterized by six to eight potential transmembrane regions, including the S4 region, the voltage-sensor of the channels. Associated with at least some K+ channels are 38- and 42-kDa peptides of unknown function. The channels give rise to non- or slow-inactivating K+ currents that are regulated through phosphorylation by both cAMP-dependent and an endogenous kinase.