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:16501573, PubMed:19953606, PubMed:21479265, PubMed:22289912, PubMed:23734863, PubMed:25756792, PubMed:26997484). 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:16501573, PubMed:19953606, PubMed:21479265, PubMed:23734863, 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). {ECO:0000250|UniProtKB:Q63959, ECO:0000269|PubMed:10712820, ECO:0000269|PubMed:16501573, ECO:0000269|PubMed:19953606, ECO:0000269|PubMed:21479265, ECO:0000269|PubMed:22289912, ECO:0000269|PubMed:23734863, ECO:0000269|PubMed:25756792, ECO:0000269|PubMed:26997484}. This is the function of KCNC3 (potassium voltage-gated channel subfamily C member 3, Ensembl gene identifier ENSG00000131398).