LOCALIZATION OF KV1.1 AND KV1.2, 2 K-CHANNEL PROTEINS, TO SYNAPTIC TERMINALS, SOMATA, AND DENDRITES IN THE MOUSE-BRAIN

Multiple voltage-gated potassium (K) channel gene products are likely to be involved in regulating neuronal excitability of any single neuro n in the mammalian brain. Here we show that two closely related voltag e-gated K channel proteins, mKv1.1 and mKv1.2, are present in multiple subcellular locations including cell somata, juxtaparanodal regions o f myelinated axons, synaptic terminals, unmyelinated axons, specialize d junctions among axons, and proximal dendrites. Staining patterns of the two channel polypeptides overlap in some areas of the brain, yet e ach has a unique pattern of expression. For example, in the hippocampu s, both mKv1.1 and mKv1.2 proteins are present in axons, often near or at synaptic terminals in the middle molecular layer of the dentate gy rus, while only mKv1.1 is detected in axons and synaptic terminals in the hilar/CA3 region. In the cerebellum, both channel proteins are loc alized to axon terminals and specialized junctions among axons in the plexus region of basket cells. Strong differential staining is observe d in the olfactory bulb, where mKv1.2 is localized to cell somata and axons, as well as to proximal dendrites of the mitral cells. This over lapping yet differential pattern of expression and specific subcellula r localization may contribute to the unique profile of excitability di splayed by a particular neuron.