Voltage-gated potassium channel that mediates transmembrane potassium transport in excitable membranes, primarily in the brain. Contributes to the regulation of the fast action potential repolarization and in sustained high-frequency firing in neurons of the central nervous system (PubMed:10561420, PubMed:10414303, PubMed:11124984, PubMed:10903572, PubMed:11506885, PubMed:15317859, PubMed:15917463, PubMed:17761775, PubMed:21414897). Homotetramer channels mediate delayed-rectifier voltage-dependent potassium currents that activate rapidly at high-threshold voltages and inactivate slowly (PubMed:10414303). Forms tetrameric channels through which potassium ions pass in accordance with their electrochemical gradient. The channel alternates between opened and closed conformations in response to the voltage difference across the membrane (By similarity). Can form functional homotetrameric and heterotetrameric channels that contain variable proportions of KCNC1, and possibly other family members as well; channel properties depend on the type of alpha subunits that are part of the channel (PubMed:10531438, PubMed:12000114). Channel properties may be modulated by either the association with ancillary subunits, such as KCNE1, KCNE2 and KCNE3 or indirectly by nitric oxide (NO) through a cGMP- and PKG-mediated signaling cascade, slowing channel activation and deactivation of delayed rectifier potassium channels (By similarity). Contributes to fire sustained trains of very brief action potentials at high frequency in thalamocortical and suprachiasmatic nucleus (SCN) neurons, in hippocampal and neocortical interneurons and in retinal ganglion cells (PubMed:10561420, PubMed:10903572, PubMed:11506885, PubMed:17761775). Sustained maximal action potential firing frequency in inhibitory hippocampal interneurons is negatively modulated by histamine H2 receptor activation in a cAMP- and protein kinase (PKA) phosphorylation-dependent manner (PubMed:10903572). Plays a role in maintaining the fidelity of synaptic transmission in neocortical GABAergic interneurons by generating action potential (AP) repolarization at nerve terminals, thus reducing spike-evoked calcium influx and GABA neurotransmitter release (PubMed:15917463). Required for long-range synchronization of gamma oscillations over distance in the neocortex (PubMed:22539821). Contributes to the modulation of the circadian rhythm of spontaneous action potential firing in suprachiasmatic nucleus (SCN) neurons in a light-dependent manner (PubMed:21414897). Inhibited by millimolar levels of tetraethylammonium (TEA). Contrary to other channels, inhibited only by millimolar levels of 4-aminopyridine (4-AP). Inhibited by Stichodactyla helianthus peptide ShK. Homotetrameric channels expressed in xenopus oocytes or in mammalian non-neuronal cells display delayed-rectifier voltage-dependent potassium currents, that are rapidly activated during membrane depolarization, i.e within a risetime of a few msec. After that, inactivates very slowly, i.e within about >800 msec. Their activation requires a threshold potential at about -10 mV, with a midpoint activation at about 12.1 mV and a steepness parameter of about 8.4 mV. The voltage-dependence of activation and inactivation and other channel characteristics vary depending on the experimental conditions, the expression system, the presence or absence of ancillary subunits and post-translational modifications. Homotetramer and heterotetramer with other channel-forming alpha subunits, such as KCNC1 (PubMed:10531438). Interacts with KCNC1 (PubMed:10531438, PubMed:12000114). Homotetramer or heterotetramer channel activity is regulated by association with modulating ancillary subunits such as KCNE1, KCNE2 and KCNE3, creating a functionally diverse range of channel complexes. Interacts with KCNE1, KCNE2 and KCNE3 (By similarity). Colocalizes with parvalbumin in globus pallidus neurons. Localizes in thalamocortical axons and synapses (By similarity). Localizes on the surface of cell somata, proximal dendrites and axonal membranes (PubMed:12000114, PubMed:10903572). Also detected throughout the neuropil (PubMed:12000114). Localized in starburst cell somata and proximal dendrite processes (PubMed:15317859). Colocalized with GABA in presynaptic terminals (PubMed:10531438). Clustered in patches in somatic and proximal dendritic membrane as well as in axons and presnypatic terminals of GABAergic interneurons; some of these patches are found near postsynaptic sites (PubMed:10531438). Weakly expressed in the brain at postnatal age day 7 (P7) and increased at P60 (PubMed:21912965). Not detectable in newborn hippocampus. Expressed weakly at P7 in the early developing hippocampus, increasing progressively and reaching a plateau of expression at P14 that is maintained throughout P51. Expressed in paravalbumin- and somatostain-containing inhibitory interneurons of the hippocampus; in the CA1/CA3 stratum oriens-alveus and stratum pyramidale and in cells within the hilus and subgranular layer of the dentate gyrus (DG) (PubMed:12000114, PubMed:10903572). Strongly expressed in parvalbumin (PV)-containing fast-spiking GABAergic inhibitor interneurons in deep cortical layers V and VI (PubMed:10531438). Also expressed in non-fast-spiking calbindin (CB)- and/or somatostatin (SOM)-containing interneurons in deep cortical layers V and VI (PubMed:10531438). Expressed in starburst amacrine cells of the retina in the inner nuclear layer (INL) and ganglion cell layer (GCL) (PubMed:15317859). Expressed in the suprachiasmatic nucleus (SCN) (at protein level) (PubMed:15852012, PubMed:21414897). Expressed in the early developing brain, increasing progressively until P14 (PubMed:21912965). Weakly expressed in the brain at 14 dpc (at protein level) (PubMed:21912965). Expressed in the brain at 14 dpc (PubMed:21912965). The transmembrane segment S4 functions as voltage-sensor and is characterized by a series of positively charged amino acids at every third position. Channel opening and closing is effected by a conformation change that affects the position and orientation of the voltage-sensor paddle formed by S3 and S4 within the membrane. A transmembrane electric field that is positive inside would push the positively charged S4 segment outwards, thereby opening the pore, while a field that is negative inside would pull the S4 segment inwards and close the pore. Changes in the position and orientation of S4 are then transmitted to the activation gate formed by the inner helix bundle via the S4-S5 linker region. Phosphorylated by PKA in cortical synaptosomes. cAMP-dependent phosphorylation inhibits channel activity (By similarity). Histamine H2 receptor- and PKA-induced phosphorylation extends action potential spike duration, reduces action potential spike amplitude, sustains maximum firing frequency in hippocampal interneurons; also reduces the incidence of high-frequency oscillations in hippocampal CA3 pyramidal cell layers (PubMed:10903572). Mice are healthy, grow normally, are fertile and show no evidence of severe sensory or motor abnormalities (PubMed:11124984). Show increased seizure susceptibility and reduced long-range synchronization of gamma oscillations over distance in the neocortex (PubMed:22539821). Thalamocortical neurons show a strong attenuation in maximal peak firing rates, with larger spikes and slower action potential repolarization (PubMed:17761775). Neocortical GABAergic interneurons display broader spikes and sustain lower trains of high-frequency spikes without accommodation or spike doublets in rapid succession (PubMed:11124984, PubMed:22539821). Histamine H2 receptor- and PKA-induced hippocampal inhibitory interneurons display no maximal sustainable firing frequency modulation (PubMed:10903572). Double knockout of KCNC2 and KCNC1 exhibited disrupted daily rhythms in wheel-running behavior (PubMed:21414897). Display smaller outward currents and slower deactivation in starburst amacrine cells compared with KCNC2 knockout mice (PubMed:15317859). Neocortical GABAergic interneuron terminals display also a reduced rate of spike repolarization, broader spike, increased calcium influx and release of GABA neurotransmitter (PubMed:15917463). Suprachiasmatic nucleus (SCN) neurons display a reduction in the magnitude of fast delayed rectifier potassium currents, wider action potentials, reduced spontaneous firing activity during the day and reduced NMDA-evoked increase firing responses during the night (PubMed:21414897). Belongs to the potassium channel family. C (Shaw) (TC 1.A.1.2) subfamily. Kv3.2/KCNC2 sub-subfamily.