KCNG4
Domain
The transmembrane segment S4 functions as a 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.
Function
Regulatory subunit of the voltage-gated potassium (Kv) channel which, when coassembled with KCNB1, modulates the kinetics parameters of the heterotetrameric channel namely the time course of activation, deactivation and inactivation and on the voltage-dependence of activation (PubMed:12060745, PubMed:19074135). Potassium channel subunit that does not form functional channels by itself (Probable) (PubMed:12060745). Reduces the deactivation rate (PubMed:12060745, PubMed:19074135). Modulates the threshold for activation by shifting by approximately 20 mV in hyperpolarizing direction (PubMed:12060745). Markedly changes the inactivation by shifting the voltage dependence of inactivation by approximately 40 mV in hyperpolarizing direction (PubMed:12060745). Acceleratee activation and enhances the time course of activation (PubMed:12060745).
Sequence Similarities
Belongs to the potassium channel family. G (TC 1.A.1.2) subfamily. Kv6.4/KCNG4 sub-subfamily.
Tissue Specificity
Highly expressed in brain, and at lower levels in liver, small intestine and colon.
Cellular localization
- Cell membrane
- Multi-pass membrane protein
- Has to be associated with KCNB1 or possibly another partner to get inserted in the plasma membrane (PubMed:19074135). Colocalizes with KCNB1 at the plasma membrane (PubMed:19074135). Retains in the endoplasmic reticulum in the absence of KCNB1 (PubMed:19074135).
Alternative names
KCNG3, KCNG4, Voltage-gated potassium channel regulatory subunit KCNG4, Potassium voltage-gated channel subfamily G member 4, Voltage-gated potassium channel subunit Kv6.3, Voltage-gated potassium channel subunit Kv6.4