Understanding Voltage -Gated Ion Channels via Molecular Archeology
Results of recent genome sequencing projects together with advances in biochemical, molecular genetic and physiological experimentation have allowed better understanding towards voltage-gated ion channels. The voltage-gated ion channels (VIC) superfamily is one of the oldest groups of membrane transporters. Members of the VIC superfamily are capable of transporting potassium, sodium and calcium ions. The voltage-gated ion channels are well known for their function in excitable tissues of eukaryotic organisms. Eukaryotic members of the VIC superfamily allow the flow of ions by sensing the change in membrane voltage. These channels are composed of multiple subunits. There are 11 families of auxiliary subunits included in this study. Each family of channels and auxiliary subunits was tabulated and analyzed phylogenetically. A phylogenetic tree is derived from sequence alignment of each family. Family-specific secondary structural traits were detected using Kyte-Doolittle hydropathy plots. We identified potential potassium channel auxiliary subunits in bacterial genomes. Novel calcium channel auxiliary subunits from insects were also identified. Auxiliary subunits of voltage-gated ion channels have been implicated as potential drug targets for epilepsy. In addition, we here report results of sequence analyses on representative sodium and calcium channels of the VIC superfamily. It is confirmed that the substrate specificity did not interconvert. The events leading to quadruplication only occurred once. The quadruplication event occurred in two distinct steps. Novel members of this superfamily were also identified.
University of Illinois - Urbana-Champaign
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University of Illinois at Urbana-Champaign