Contrasting lmmunohistochemical Localizations Novel K+ Channels of the Shah Subfamily Two

We have localized CDRK and DRKl, two novel K+ channels of the Shab subfamily by immunohistochemistry. The two channels are closely related in structure with about 90% amino acid identity in the N-terminal and middle portions and 60% identity in the C-terminal region. We observe striking differences in cellular localizations of the two channels. DRKl tends to localize to cell bodies and proximal dendrites discretely, while CDRK is diffusely present in cell bodies and is also found on fibers in specific brain areas. In the cerebral cortex DRKl is localized to pyramidal cells, whereas CDRK occurs in small cells, presumably interneurons. These localizations may reflect specialized delayed rectifier functions and targeting properties manifested differentially by K+ channel subfamily members. [