Associates with KCNQ2 or KCNQ5 to form a potassium channel with essentially identical properties to the channel underlying the native M-current, a slowly activating and deactivating potassium conductance which plays a critical role in determining the subthreshold electrical excitability of neurons as well as the responsiveness to synaptic inputs. Therefore, it is important in the regulation of neuronal excitability. Heterotetramer with KCNQ2; form the heterotetrameric M potassium channel. Interacts with calmodulin; the interaction is calcium-independent, constitutive and participates in the proper assembly of a functional heterotetrameric M channel. Heteromultimer with KCNQ5. May associate with KCNE2. Interacts with IQCJ-SCHIP1 (By similarity). The segment S4 is probably the voltage-sensor and is characterized by a series of positively charged amino acids at every third position. KCNQ2/KCNQ3 are ubiquitinated by NEDD4L. Ubiquitination leads to protein degradation. Degradation induced by NEDD4L is inhibited by USP36. Belongs to the potassium channel family. KQT (TC 1.A.1.15) subfamily. Kv7.3/KCNQ3 sub-subfamily.