Voltage-gated potassium channel that plays an important role in the rapid repolarization of fast-firing brain neurons. The channel opens in response to the voltage difference across the membrane, forming a potassium-selective channel through which potassium ions pass in accordance with their electrochemical gradient (PubMed:2599109, PubMed:1400413). Can form functional homotetrameric channels and heterotetrameric channels that contain variable proportions of KCNC2, and possibly other family members as well. Contributes to fire sustained trains of very brief action potentials at high frequency in pallidal neurons. Heteromultimer with KCNG3, KCNG4 and KCNV2 (By similarity). Heteromultimer with KCNC2 (By similarity). Heterotetramer with KCNC3 (By similarity). Interacts with the ancillary subunits KCNE1 and KCNE2; the interaction modulates channel activity (By similarity). Localizes in parallel fiber membranes, distributed on the perisynaptic and extrasynaptic membranes away from the active zones. Detected in cerebellum (PubMed:11517255, PubMed:15217387). Detected in brain (at protein level) (PubMed:9037088). Detected in brain (PubMed:9037088). The segment S4 is probably the voltage-sensor and is characterized by a series of positively charged amino acids at every third position. The tail may be important in modulation of channel activity and/or targeting of the channel to specific subcellular compartments. N-glycosylated; contains sialylated glycans. Mutant mice are born at the expected Mendelian rate. They are viable and fertile, but have lower body weight than wild-type. They have normal spontaneous locomotor activity, but impaired motor skills (PubMed:9037088). Mice lacking both Kcnc3 and Kcnc1 are born at the expected Mendelian rate, but the pups do not thrive and all die about 26 days after birth when kept together with other littermates. Their failure to thrive may be due to motor problems; mutant pups survive when fed separately, but 45 days after birth their body weight is only 50 to 60 % of that of wild-type (PubMed:11517255). They appear uncoordinated and display severe ataxia, myoclonus and spontaneous whole-body muscle jerks, but display no obvious alterations in brain morphology (PubMed:11517255, PubMed:15217387, PubMed:16923152). Mutant mice are also much more sensitive to ethanol and fall sideways at ethanol concentrations that have no effect on wild-type mice (PubMed:11517255). They display increased locomotor and exploratory activity (PubMed:11517255, PubMed:15217387). Mice lacking Kcnc1 show reduced response to tremorogenic agent harmaline; mice lacking both Kcnc3 and Kcnc1 are resistant to the tremorogenic agent harmaline (PubMed:15217387). Belongs to the potassium channel family. C (Shaw) (TC 1.A.1.2) subfamily. Kv3.1/KCNC1 sub-subfamily.