Potassium channel subunit that does not form functional channels by itself. Can form functional heterotetrameric channels with KCNB1; modulates the delayed rectifier voltage-gated potassium channel activation and deactivation rates of KCNB1 (PubMed:19074135). Heterotetramer with KCNB1 (PubMed:19074135). Colocalizes with KCNB1 at the plasma membrane (PubMed:19074135). Expressed in brain and placenta, and at much lower levels in kidney and pancreas (PubMed:9434767). 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. Belongs to the potassium channel family. G (TC 1.A.1.2) subfamily. Kv6.1/KCNG1 sub-subfamily.