title: Coassembly of big conductance Ca2+-activated K+ channels and L-type voltage-gated Ca2+ channels in rat brain.
abstract: Based on electrophysiological studies, Ca(2+)-activated K(+) channels and voltage-gated Ca(2+) channels appear to be located in close proximity in neurons. Such colocalization would ensure selective and rapid activation of K(+) channels by local increases in the cytosolic calcium concentration. The nature of the apparent coupling is not known. In the present study we report a direct coassembly of big conductance Ca(2+)-activated K(+) channels (BK) and L-type voltage-gated Ca(2+) channels in rat brain. Saturation immunoprecipitation studies were performed on membranes labeled for BK channels and precipitated with antibodies against alpha(1C) and alpha(1D) L-type Ca(2+) channels. To confirm the specificity of the interaction, precipitation experiments were carried out also in reverse order. Also, additive precipitation was performed because alpha(1C) and alpha(1D) L-type Ca(2+) channels always refer to separate ion channel complexes. Finally, immunochemical studies showed a distinct but overlapping expression pattern of the two types of ion channels investigated. BK and L-type Ca(2+) channels were colocalized in various compartments throughout the rat brain. Taken together, these results demonstrate a direct coassembly of BK channels and L-type Ca(2+) channels in certain areas of the brain.
authors.affiliation: Department of Medical Physiology, the Panum Institute, University of Copenhagen, Blegdamsvej 3, Copenhagen DK-2200, Denmark. mgrunnet@mfi.ku.dk
authors.forename: Morten
authors.initials: M
authors.lastname: Grunnet
authors.forename: Walter A
authors.initials: WA
authors.lastname: Kaufmann
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D020746:Calcium Channels, L-Type / Q000737:chemistry / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D002531:Cerebellum / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D004306:Dose-Response Relationship, Immunologic; D004594:Electrophysiology; D015151:Immunoblotting; D007120:Immunochemistry; D007150:Immunohistochemistry; D007477:Ions; D051036:Large-Conductance Calcium-Activated Potassium Channels; D008024:Ligands; D009474:Neurons / Q000378:metabolism; D015221:Potassium Channels / Q000737:chemistry; D024681:Potassium Channels, Calcium-Activated / Q000737:chemistry / Q000378:metabolism*; D011233:Precipitin Tests; D011485:Protein Binding; D051381:Rats; D017208:Rats, Wistar
chemical_list: D020746:Calcium Channels, L-Type; D007477:Ions; D051036:Large-Conductance Calcium-Activated Potassium Channels; D008024:Ligands; D015221:Potassium Channels; D024681:Potassium Channels, Calcium-Activated; D002118:Calcium