UC Irvine

Voltage-gated ion channels contain a voltage-sensing domain and a pore domain. Two families of proteins have been identified that contain the voltage-sensing domain but no pore domain, the family of voltage-sensitive phosphatases and the family of voltage-gated proton channels. Hv1, the only known voltage-gated proton channel, has clinical relevance, having been found at high expression levels in cancer cell lines, and the inhibition of Hv1 has shown to slow the growth of cancer cells. Previously, there were no known blockers of this channel that could be developed for therapeutic use. Here I have identified two intracellular blockers of Hv1. The first, 2GBI, is an open channel blocker accessible from the intracellular side. The second, ClGBI, is also an open channel blocker but accessible from the extracellular side. Through mutagenesis of the Hv1 channel and electrophysiology techniques, we have investigated the binding environment of this inhibitor and studied the mechanism of intracellular gating in Hv1. Next, due to the clinical significance of Hv1, we searched for related voltage-sensitive proteins without a pore domain, and identified Hv1's closest related protein, called HVRP1. Using a combination of techniques including in situ hybridization, immunocytochemistry, and electrophysiology, I have begun initial characterization of this new member of the family of voltage-sensitive proteins without a pore domain. The novelty of this research represents an entirely new family of proteins whose function is yet unknown, but likely to be a function yet unassociated with pore-domain-lacking voltage-sensitive proteins.