KCR1, a Membrane Protein That Facilitates Functional Expression of Non-inactivating K+ Currents Associates with Rat EAG Voltage-dependent K+Channels

Cerebellar granule neurons possess a non-inactivating K+ current, which controls resting membrane potentials and modulates the firing rate by means of muscarinic agonists. kcr1 was cloned from the cerebellar cDNA library by suppression cloning. KCR1 is a novel protein with 12 putative transmembrane domains and enhances the functional expression of the cerebellar non-inactivating K+ current in Xenopus oocytes. KCR1 also accelerates the activation of rat EAG K+ channels expressed in Xenopus oocytes or in COS-7 cells. Far-Western blotting revealed that KCR1 and EAG proteins interacted with each other by means of their C-terminal regions. These results suggest that KCR1 is the regulatory component of non-inactivating K+ channels.