Structural dynamics of hERG potassium channel gating studied using voltage clamp fluorimetry

Ion channels are cardiac membrane proteins that control the flow of ions like sodium and potassium in and out of heart cells, regulating both cardiac electrical impulses and the contractions associated with the heart beating. Voltage-gated potassium channels, such as the human ether-a-go-go related gene (hERG). are a class of ion channels that open and close – an action known as gating – in response to changes in the electrical potential across the cell’s plasma membrane. In the heart, hERG channels play a crucial role in regulating heart rate and rhythm. Reduced hERG channel function has been associated with loss of the normal heart rhythm and sudden cardiac death. The unique role played by hERG channels in the heart is a result of their unusual gating properties. However, there is limited knowledge about the molecular mechanisms of these gating processes and how they are modulated.

Dr. Tom Claydon is using a new fluorescence technique that he established as a post doctoral fellow that provides a real-time analysis of the protein motions that cause hERG channels to open and close. With a small fluorescent probe attached directly to the channel protein, Claydon’s team can directly study movements that occur within the channel as it opens and closes and measure the electrical current passing through the channel during this activity. Only a handful of researchers worldwide are currently using fluorescence experiments to study ion channel gating. These experiments will provide a comprehensive and unparalleled view of hERG channel function and how it is modulated in health and disease. An understanding of these processes will lay the foundation for new therapies for cardiovascular disease.