VOLTAGE-GATED K-SUBUNITS - EXPRESSION AND DISTRIBUTION OF KV-BETA-1 AND KV-BETA-2 IN ADULT-RAT BRAIN( CHANNEL BETA)

Recent cloning of K+ channel beta subunits revealed that these cytopla smic polypeptides can dramatically alter the kinetics of current inact ivation and promote efficient glycosylation and surface expression of the channel-forming alpha subunits. Here, we examined the expression, distribution, and association of two of these beta subunits, Kv beta 1 and Kv beta 2, in adult rat brain. In situ hybridization using cRNA p robes revealed that these beta-subunit genes are heterogeneously expre ssed, with high densities of KV beta 1 mRNA in the striatum, CA1 subfi eld of the hippocampus, and cerebellar Purkinje cells, and high densit ies of KV beta 2 mRNA in the cerebral cortex, cerebellum, and brainste m. immunohistochemical staining using subunit-specific monoclonal and affinity-purified polyclonal antibodies revealed that the KV beta 1 an d Kv beta 2 polypeptides frequently cc-localize and are concentrated i n neuronal perikarya, dendrites, and terminal fields, and in the juxta paranodal region of myelinated axons. Immunoblot and reciprocal co-imm unoprecipitation analyses indicated that Kv beta 2 is the major beta s ubunit present in rat brain membranes, and that most K+ channel comple xes containing KV beta 1 also contain KV beta 2. Taken together, these data suggest that KV beta 2 is a component of almost all K+ channel c omplexes containing Kv1 alpha subunits, and that individual channels m ay contain two or more biochemically and functionally distinct beta-su bunit polypeptides.