Potassium voltage-gated channel subfamily S member 3
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
Potassium channel regulatory subunit that modulates the delayed rectifier potassium channel activity of KCNB1 by namely slowing down the deactivation and inactivation time constants (PubMed:10484328). While it does not form functional channel on its own, it can form functional heterotetrameric channels with KCNB1 (PubMed:10484328).
Sequence Similarities
Belongs to the potassium channel family. S (TC 1.A.1.2) subfamily. Kv9.3/KCNS3 sub-subfamily.
Tissue Specificity
Detected in whole normal term placental and placental chorionic plate arteries and veins. Detected in syncytiotrophoblast and in blood vessel endothelium within intermediate villi and chorionic plate (at protein level) (PubMed:22943705). Detected in most tissues, but not in peripheral blood lymphocytes. The highest levels of expression are in lung (PubMed:10484328).
Cellular localization
- Cell membrane
- Multi-pass membrane protein
- May not reach the plasma membrane but remain in an intracellular compartment in the absence of KCNB1 (PubMed:10484328).
Alternative names
Delayed-rectifier potassium channel regulatory subunit KCNS3, Delayed-rectifier K(+) channel alpha subunit 3, Delayed-rectifier potassium channel subunit Kv9.3, Potassium voltage-gated channel subfamily S member 3, Kv9.3, KCNS3