Syntaxin 1A co-associates with native rat brain and cloned large conductance, calcium-activated potassium channels in situ.

Large conductance, calcium-activated potassium channels (BKCa channels) are regulated by several distinct mechanisms, including phosphorylation/dephosphorylation events and protein-protein interactions. In this study, we have examined the interaction between BKCa channels and syntaxin 1A, a soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) that is reported to modulate the activity and/or localization ...
of different classes of ion channels. Using a reciprocal co-immunoprecipitation strategy, we observed that native BKCa channels in rat hippocampus co-associate with syntaxin 1A, but not the closely related homologue syntaxin 3. This BKCa channel-syntaxin 1A interaction could be further demonstrated in a non-neuronal cell line (human embryonic kidney (HEK) 293 cells) following co-expression of rat syntaxin 1A and BKCa channels cloned from either mouse brain or bovine aorta. However, co-expression of these same channels with syntaxin 3 did not lead to a detectable protein-protein interaction. Immunofluorescent co-staining of HEK 293 cells expressing BKCa channels and syntaxin 1A demonstrated overlapping distribution of these two proteins in situ. Functionally, co-expression of BKCa channels with syntaxin 1A, but not syntaxin 3, was observed to enhance channel gating and kinetics at low concentrations (1-4 microM) of free cytosolic calcium, but not at higher concentrations (< or = 10 microM), as judged by macroscopic current recordings in excised membrane patches. Interactions between BKCa channels and neighbouring membrane proteins may thus play important roles in regulating the activity and/or distribution of these channels within specialized cellular compartments.
Mesh Terms:
Animals, Antigens, Surface, Aorta, Thoracic, Blotting, Western, Brain Chemistry, Cattle, Cell Line, Cloning, Molecular, Cytosol, DNA, Complementary, Electrophysiology, Hippocampus, Humans, Immunohistochemistry, Kidney, Membrane Proteins, Nerve Tissue Proteins, Plasmids, Potassium Channels, Potassium Channels, Calcium-Activated, Potassium Channels, Voltage-Gated, Precipitin Tests, Protein Binding, Qa-SNARE Proteins, Rats, Syntaxin 1, Transfection
J. Physiol. (Lond.)
Date: Nov. 15, 2003
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