Roles of surface residues of intracellular domains of heag potassium channels |
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Authors: | Louisa Stevens Min Ju Dennis Wray |
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Institution: | (1) Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK |
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Abstract: | Ether-a-go-go potassium channels have large intracellular regions containing ‘Per-Ant-Sim’ (PAS) and cyclic nucleotide binding
(cNBD) domains at the N- and C-termini, respectively. In heag1 and heag2 channels, recent studies have suggested that the
N- and C-terminal domains interact, and affect activation properties. Here, we have studied the effect of mutations of residues
on the surfaces of PAS and cNBD domains. For this, we introduced alanine and lysine mutations in heag1 channels, and recorded
currents by two-electrode voltage clamp. In both the PAS domain and the cNBD domain, contiguous areas of conserved residues
on the surfaces of these domains were found which affected the activation kinetics of the channel. Next, we investigated possible
effects of mutations on domain interactions of PAS and cNBD proteins in heag2 by co-expressing these domain proteins followed
by analysis with native gels and western blotting. We found oligomeric association between these domains. Mutations F30A and
A609K (on the surfaces of the PAS and cNBD domains, respectively) affected oligomeric compositions of these domains when proteins
for PAS and cNBD domains were expressed together. Taken together, the data suggest that the PAS and cNBD domains form interacting
oligomers that have roles in channel function. |
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Keywords: | Ion channels Potassium channels Electrophysiology Alanine scanning Ether-a-go-go channels |
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