Associates with KCNQ3 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. KCNQ2 current is blocked by barium and tetraethylammonium whereas 4-aminopyridine and charybdotoxin have no effect on KCNQ2 current. Tyrosine kinase inhibitors genistein or herbimycin a markedly down-regulate KCNQ2 current. As the native M-channel, the potassium channel composed of KCNQ2 and KCNQ3 is also suppressed by activation of the muscarinic acetylcholine receptor CHRM1. Heterotetramer with KCNQ3; form the heterotetrameric M potassium channel (PubMed:11230508). Interacts with calmodulin; the interaction is calcium-independent, constitutive and participates in the proper assembly of a functional heterotetrameric M channel. May associate with KCNE2 (By similarity). Interacts with IQCJ-SCHIP1 (By similarity). Splice isoforms fell into three classes, those that contain an in frame exon 16 (Isoforms A-I) those that contain an out-of-frame exon 16 due to an alternative splice junction in exon 14 and those that terminate prematurely to exon 16. Only the forms containing an in frame exon 16 are able to form functional channels. A similar splice pattern is also produced for splice variants that contain an out-of-frame exon 16. A wide variety of different truncated isoforms were isolated for splice variants that terminate prematurely to exon 16. Expressed in brain and sympathetic ganglia. In brain, expressed in cortex, hippocampus, and cerebellum. In sympathetic ganglia, expressed at lower levels in celiac ganglia and superior mesenteric ganglia than in superior cervical ganglia. 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 heteromeric current can be increased by intracellular cyclic AMP, an effect that depends on phosphorylation of Ser-52 in the N-terminal region. KCNQ2/KCNQ3 are ubiquitinated by NEDD4L. Ubiquitination leads to protein degradation. Degradation induced by NEDD4L is inhibited by USP36. When coexpressed with KCNQ3 subunit in CHO cells or Xenopus oocytes, isoform B was found to have significantly different deactivation-activation kinetics. The kinetics was 2.5 times more slowly than the kinetics of other isoforms. The presence of exon 15a in isoform B accounts for the slow deactivation-activation kinetics. Alternative splicing of the KCNQ2 gene may contribute to the variation in M-current kinetics seen in vivo. Belongs to the potassium channel family. KQT (TC 1.A.1.15) subfamily. Kv7.2/KCNQ2 sub-subfamily.