A novel potassium channel protein expressed exclusively in the brain: a gene encoding this protein; a vector containing this gene; a host cell containing this vector; etc. A typical method for obtaining the above protein is as follows: mRNA is extracted from human cells or tissue capable of producing the target potassium channel protein. Then use is made of two primers between which the channel protein mRNA or a part of the mRNA region is located by using the thus extracted mRNA as a template. By effecting a reverse transcriptase-polymerase chain reaction (RT-PCR), the channel protein cDNA or a part thereof can be obtained. The obtained novel potassium channel cDNA or a part of the same is integrated into an appropriate expression vector and then expressed in a host cell. The target protein can be thus produced.
