We have studied a unique type of subconductance behavior mediated by dendrotoxins from mamba snake venom and BPTI (bovine pancreatic trypsin inhibitor), small structurally related proteins that bind to an intracellular site on BKCa channels. Opening of the BKCa channel is proposed to be activated by binding of Ca2+ to specific sites on the large intracellular domain. We have shown that a C-terminal fragment of the Drosophila BKCa channel exhibits 45Ca2+ binding activity using a protein blot overlay assay. We are working to extend these findings by expressing BKCa channels tagged with fluorescent jellyfish protein domains such as CFP and YFP. We hypothesize that Ca2+ binding to such tagged BKCa channels may exhibit fluorescence changes that can be used to analyze Ca2+ binding. We have also investigated the physical basis of modulation of BKCa channel conductance by different classes of phospholipids using planar bilayer reconstitution. Recently, we synthesized a novel biotinylated derivative of the scorpion toxin, iberiotoxin, that has high affinity for an extracellular blocking site on the channel. We are applying this toxin derivative to fluoresence imaging of BKCa channels in living cells and other biochemical applications.

This website was created by Melissa Bell, Lindsay Schwarting, and Niall Mangan. Updates by Niall Mangan. All information and images on this site are ©Clarkson University Laboratory of Molecular Neuroscience.