CLONING OF A BOVINE VOLTAGE-GATED K+ CHANNEL GENE UTILIZING PARTIAL AMINO-ACID-SEQUENCE OF A DENDROTOXIN-BINDING PROTEIN FROM BRAIN CORTEX

Several variants of fast-activating, voltage-dependent K+ channels exist in the nervous system where they control cell excitability and synaptic transmission, some of which are blocked selectively by alpha-dendrotoxin. Cloning of a K+ channel from bovine genomic DNA was achieved using a primer based on the N-terminal sequence of the larger subunit from the purified toxin acceptor, in conjunction with secondary primers, in the polymerase chain reaction. The resultant amino acid sequence is highly homologous to RCK 5 already cloned from rat brain, which yields a K+ current susceptible to alpha-dendrotoxin, when expressed in oocytes. These findings establish conclusively that the extensively characterised alpha-dendrotoxin acceptor is a K+ channel protein.