Probably important in the regulation of neuronal excitability. May underlie a potassium current involved in regulating the excitability of sensory cells of the cochlea. Homotetramer. May form heteromultimers with KCNQ3 (By similarity). Interacts with HSP90AB1; promotes cell surface expression of KCNQ4 (By similarity). Situated at the basal membrane of cochlear outer hair cells. Expressed in both the inner (IHCs) and the outer hair cells (OHCs) of the cochlea. Reciprocal longitudinal gradients of expression is present in IHCs and OHCs. The strongest expression in IHCs is in the base of the cochlea and in the apex for OHCs. A basal to apical gradient of expression is also present in both type I and type II spiral ganglion cells. At P0 expression is primarily in the basal hook to lower middle turn of the cochlea and progressively expands toward the apex over time. By P8, the expression is evident in both IHCs and OHCs along the entire length of the cochlea. Then the adult pattern begins to emerge, as expression in basal OHCs and in apical IHCs decreases. The segment S4 is probably the voltage-sensor and is characterized by a series of positively charged amino acids at every third position. Belongs to the potassium channel family. KQT (TC 1.A.1.15) subfamily. Kv7.4/KCNQ4 sub-subfamily.