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. The channel displays rapid activation and inactivation kinetics (PubMed:10712820, PubMed:26997484, PubMed:22289912, PubMed:23734863, PubMed:16501573, PubMed:19953606, PubMed:21479265, PubMed:25756792). It plays a role in the regulation of the frequency, shape and duration of action potentials in Purkinje cells. Required for normal survival of cerebellar neurons, probably via its role in regulating the duration and frequency of action potentials that in turn regulate the activity of voltage-gated Ca(2+) channels and cellular Ca(2+) homeostasis (By similarity). Required for normal motor function (PubMed:23734863, PubMed:16501573, PubMed:19953606, PubMed:21479265, PubMed:25756792). Plays a role in the reorganization of the cortical actin cytoskeleton and the formation of actin veil structures in neuronal growth cones via its interaction with HAX1 and the Arp2/3 complex (PubMed:26997484). Homotetramer. Heterotetramer with KCNC1 (PubMed:23734863). Interacts (via C-terminus) with HAX1 (PubMed:26997484). Identified in a complex with ACTR3, a subunit of the Arp2/3 complex; this interaction is indirect and depends on the presence of HAX1 (PubMed:26997484). Interaction with HAX1 modulates channel gating (PubMed:26997484). Detected on Purkinje cell dendritic spines, positioned perisynaptically but also in extrasynaptic positions along the spine membranes (By similarity). Detected at presynaptic calices of Held (By similarity). Colocalizes with the cortical actin cytoskeleton and the Arp2/3 complex (PubMed:26997484). The segment S4 is probably the voltage-sensor and is characterized by a series of positively charged amino acids at every third position. The cytoplasmic N-terminus mediates N-type inactivation. The C-terminal cytoplasmic tail contributes to the regulation of channel inactivation and to the interaction with HAX1 and the Arp2/3 complex. N-glycosylated. The disease is caused by variants affecting the gene represented in this entry. Belongs to the potassium channel family. C (Shaw) (TC 1.A.1.2) subfamily. Kv3.3/KCNC3 sub-subfamily.