Distribution of M-channel subunits KCNQ2 and KCNQ3 in rat hippocampus

► We used specific antibodies against KCNQ2 and KCNQ3 K+ channels in rat hippocampus. ► Localization of these “M-type” K+ channels was visualized by confocal microscopy. ► Strong expression was found in axon initial segments, but little at synaptic sites. ► Most of these channels were KCNQ2/3 heteromers, with some KCNQ2 or KCNQ3 homomers. ► KCNQ3, but not KCNQ2, was found in the lateral ventricles, of unknown function.