This protein mediates the voltage-dependent potassium ion permeability of excitable membranes. Assuming opened or closed conformations in response to the voltage difference across the membrane, the protein forms a potassium-selective channel through which potassium ions may pass in accordance with their electrochemical gradient.
Defects in KCNC3 are the cause of spinocerebellar ataxia type 13 (SCA13) [MIM:605259]. Spinocerebellar ataxia is a clinically and genetically heterogeneous group of cerebellar disorders. Patients show progressive incoordination of gait and often poor coordination of hands, speech and eye movements, due to degeneration of the cerebellum with variable involvement of the brainstem and spinal cord. SCA13 is an autosomal dominant cerebellar ataxia (ADCA) characterized by slow progression and variable age at onset, ranging from childhood to late adulthood. Mental retardation can be present in some patients.
Belongs to the potassium channel family. C (Shaw) (TC 1.A.1.2) subfamily. Kv3.3/KCNC3 sub-subfamily.
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.