TY - JOUR

T1 - Coassembly of big conductance Ca2+-activated K+ channels and L-type voltage-gated Ca2+ channels in rat brain.

AU - Grunnet, Morten

AU - Kaufmann, Walter A

N1 - Keywords: Animals; Brain; Calcium; Calcium Channels, L-Type; Cell Membrane; Cerebellum; Cytosol; Dose-Response Relationship, Immunologic; Electrophysiology; Immunoblotting; Immunochemistry; Immunohistochemistry; Ions; Large-Conductance Calcium-Activated Potassium Channels; Ligands; Neurons; Potassium Channels; Potassium Channels, Calcium-Activated; Precipitin Tests; Protein Binding; Rats; Rats, Wistar

PY - 2004

Y1 - 2004

N2 - 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.

AB - 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.

U2 - 10.1074/jbc.M402254200

DO - 10.1074/jbc.M402254200

M3 - Journal article

C2 - 15210719

VL - 279

SP - 36445

EP - 36453

JO - Journal of Biological Chemistry

JF - Journal of Biological Chemistry

SN - 0021-9258

IS - 35

ER -