Related Experiment Video
Updated: Dec 26, 2025

Recapitulation of an Ion Channel IV Curve Using Frequency Components
Published on: February 8, 2011
Gating mechanism of hyperpolarization-activated HCN pacemaker channels
Rosamary Ramentol1, Marta E Perez1, H Peter Larsson2
1Department of Physiology and Biophysics, University of Miami, Miami, FL, 33136, USA.
Abstract:
Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels are essential for rhythmic activity in the heart and brain, and mutations in HCN channels are linked to heart arrhythmia and epilepsy. HCN channels belong to the family of voltage-gated K+ (Kv) channels. However, why HCN channels are activated by hyperpolarization whereas Kv channels are activated by depolarization is not clear. Here we reverse the voltage dependence of HCN channels by mutating only two residues located at the interface between the voltage sensor and the pore domain such that the channels now open upon depolarization instead of hyperpolarization. Our data indicate that what determines whether HCN channels open by hyperpolarizations or depolarizations are small differences in the energies of the closed and open states, due to different interactions between the voltage sensor and the pore in the different channels.
Related Concept Videos
G-Protein Gated Ion Channels
Sensory...
Ligand-Gated Ion Channel Receptor: Gating Mechanism
Mechanically-gated Ion Channels
Non-gated Ion Channels
Compared to the gated ion channels, the non-gated channels, also known as leakage or passive channels, have no gating mechanism....
Ligand-gated Ion Channels
Three Subfamilies of Ligand-gated Ion Channels
Ligand-gated ion channels fall into three subfamilies. The 'Cys-loop' includes the nicotinic acetylcholine receptors, γ-aminobutyric acid (GABA), glycine, and 5-hydroxytryptamine receptors. The second one is the 'Pore-loop' channels that...
Voltage-gated Ion Channels
Generally, all voltage-gated ion channels have a 'voltage-sensing domain' that spans the lipid bilayer. The charged residues in the sensor move in response to the membrane potential changes that open the channel allowing ions movement. There are several...

