Associates with KCNQ3 to form a potassium channel which contributes to M-type current, a slowly activating and deactivating potassium conductance which plays a critical role in determining the subthreshold electrical excitability of neurons. Therefore, it is important in the regulation of neuronal excitability. May contribute, with other potassium channels, to the molecular diversity of a heterogeneous population of M-channels, varying in kinetic and pharmacological properties, which underlie this physiologically important current. Insensitive to tetraethylammonium, but inhibited by barium, linopirdine and XE991. Activated by niflumic acid and the anticonvulsant retigabine. As the native M-channel, the potassium channel composed of KCNQ3 and KCNQ5 is also suppressed by activation of the muscarinic acetylcholine receptor CHRM1. Heteromultimer with KCNQ3 (PubMed:11159685, PubMed:10787416). Heterotetramer with KCNQ1; has a voltage-gated potassium channel activity (PubMed:24855057). Strongly expressed in brain and skeletal muscle. In brain, expressed in cerebral cortex, occipital pole, frontal lobe and temporal lobe. Lower levels in hippocampus and putamen. Low to undetectable levels in medulla, cerebellum and thalamus. The segment S4 is probably the voltage-sensor and is characterized by a series of positively charged amino acids at every third position. The disease is caused by variants affecting the gene represented in this entry. Belongs to the potassium channel family. KQT (TC 1.A.1.15) subfamily. Kv7.5/KCNQ5 sub-subfamily. Truncated N-terminus.