THALAMOCORTICAL PROJECTIONS HAVE A K-DEPENDENT PROTEIN-KINASE( CHANNEL THAT IS PHOSPHORYLATED AND MODULATED BY CAMP)

The finding that some K+ channel mRNAs are restricted to certain popul ations of neurons in the CNS suggests that there are K+ channels tailo red to certain neuronal circuits. One such example are the transcripts from the KV3.2 gene, the majority of which are expressed in thalamic relay neurons. To gain insights into the specific roles of KV3.2 subun its, site specific antibodies were raised to determine their localizat ion in thalamic relay neurons. Immunohistochemical and focal lesioning studies demonstrate that KV3.2 proteins are localized to the terminal fields of thalamocortical projections, It is also strewn that KV3.2 c hannels expressed in vitro are strongly inhibited through phosphorylat ion by cAMP-dependent protein kinase (PKA). Channels containing KV3.1 subunits, which otherwise exhibit nearly identical electrophysiologica l properties in heterologous expression systems but have a different a nd less restricted pattern of expression in the CNS, are not affected by PKA. Therefore, this modulation might be associated with the specif ic roles of KV3.2 subunits. Furthermore, we demonstrate that KV3.2 pro teins can be phosphorylated in situ by intrinsic PKA. KV3.2 subunits d isplay properties and have a localization consistent with a role in th e regulation of the efficacy of the thalamocortical synapse, and could thereby participate in the neurotransmitter-mediated control of funct ional states of the thalamocortical system associated with global stat es of awareness.