Conservation of Ether-a-go-go Family Potassium Channels in Cnidarians
Open Access
- Author:
- Martinson, Alexandra Sophia
- Area of Honors:
- Biology
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- Timothy J Jegla, Thesis Supervisor
Dr. Stephen Wade Schaeffer, Thesis Honors Advisor - Keywords:
- potassium channel
electrophysiology - Abstract:
- The Ether-a-go-go family of potassium channels consists of three functionally independent gene families, Eag (Kv10), Erg (Kv11) and Elk (Kv12), conserved between insects and mammals. All three gene families encode sub-threshold voltage-gated potassium channels with distinct biophysical properties. Ether-a-go-go family channels differ from other potassium channels by the presence of a distinct complement of cytoplasmic modulatory domains (EAG, PAS, cNBD) that regulate channel function. We characterized the Ether-a-go-go family in a cnidarian, Nematostella vectensis (starlet sea anemone), to determine which properties of these channels have been conserved throughout the history of the nervous system. Cnidarians diverged from the vertebrate line early in metazoan evolution and the first nervous system evolved in a late common ancestor of vertebrates and Cnidarians. We find that all three gene families (Eag, Erg and Elk) are present and highly conserved in Nematostella. The Nematostella Eag and Elk families are represented by a single gene (NvEag1 and NvElk1), whereas the Nematostella Erg family has been expanded to five genes (NvErg1-5). NvErg2-5 interestingly lack the characteristic EAG and PAS domains at the N-terminus. We examined functional conservation by comparing the properties of NvEag1 and NvErg1 currents to currents produced by their mammalian orthologs Mouse Eag2 and Mouse Erg3. We find that the distinctive gating characteristics of Eag and Erg genes are conserved between mammals and Cnidarians. Like mammalian Ether-a-go-go family channels, the Nematostella channels are highly sensitive to changes in external pH. Their pH sensitivity is influenced by Ether-a-go-go family-specific acidic charges in the voltage sensor.