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Related Concept Videos

Non-gated Ion Channels01:24

Non-gated Ion Channels

Ion channels are specialized proteins on the plasma membrane that allow charged ions to pass down their electrochemical gradient. Their main function is to maintain the membrane potential which is critical for cell viability. These channels are either gated or non-gated and can transport more than a thousand ions within milliseconds for the cellular event to occur.
Compared to the gated ion channels, the non-gated channels, also known as leakage or passive channels, have no gating mechanism.
Non-gated Ion Channels01:24

Non-gated Ion Channels

Ion channels are specialized proteins on the plasma membrane that allow charged ions to pass down their electrochemical gradient. Their main function is to maintain the membrane potential which is critical for cell viability. These channels are either gated or non-gated and can transport more than a thousand ions within milliseconds for the cellular event to occur.
Compared to the gated ion channels, the non-gated channels, also known as leakage or passive channels, have no gating mechanism.
Voltage-gated Ion Channels01:26

Voltage-gated Ion Channels

Voltage-gated ion channels are transmembrane proteins that open and close in response to changes in the membrane potential. They are present on the membranes of all electrically excitable cells such as neurons, heart, and muscle cells.
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 types of...
Voltage-gated Ion Channels01:26

Voltage-gated Ion Channels

Voltage-gated ion channels are transmembrane proteins that open and close in response to changes in the membrane potential. They are present on the membranes of all electrically excitable cells such as neurons, heart, and muscle cells.
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 types of...
The Role of Ion Channels in Neuronal Computation01:19

The Role of Ion Channels in Neuronal Computation

A postsynaptic neuron usually receives numerous impulses from several other presynaptic neurons. The axon hillock of the postsynaptic neuron integrates all these signals and determines the likelihood of firing an action potential.
Sometimes a single EPSP is strong enough to induce an action potential in the postsynaptic neuron. However, multiple presynaptic inputs must often create EPSPs around the same time for the postsynaptic neuron to be sufficiently depolarized to fire an action potential.
Pore Transport and Ion-Pair Transport01:17

Pore Transport and Ion-Pair Transport

Pore transport and ion-pair formation are critical mechanisms for the absorption and distribution of drugs in the body.
Pore transport, also known as convective transport, is a process where small molecules like urea, water, and sugars rapidly cross cell membranes as though there were channels or pores in the membrane. Although direct microscopic evidence is limited  but the concept of pores or channels is widely accepted based on physiological evidence. Despite the lack of direct microscopic...

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Related Experiment Video

Updated: May 21, 2026

Study of the Functions and Activities of Neuronal K-Cl Co-Transporter KCC2 Using Western Blotting
10:08

Study of the Functions and Activities of Neuronal K-Cl Co-Transporter KCC2 Using Western Blotting

Published on: December 9, 2022

Pore determinants of KCNQ3 K+ current expression.

Frank S Choveau1, Ciria C Hernandez, Sonya M Bierbower

  • 1Department of Physiology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA.

Biophysical Journal
|June 21, 2012
PubMed
Summary
This summary is machine-generated.

Mutations in the KCNQ3 channel pore region significantly reduce KCNQ3 and KCNQ2/3 channel currents. These pore helix mutations lock the selectivity filter, preventing ion flow and explaining reduced KCNQ channel activity.

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Isolation and Kv Channel Recordings in Murine Atrial and Ventricular Cardiomyocytes
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Mutagenesis and Functional Analysis of Ion Channels Heterologously Expressed in Mammalian Cells
15:28

Mutagenesis and Functional Analysis of Ion Channels Heterologously Expressed in Mammalian Cells

Published on: October 1, 2010

Related Experiment Videos

Last Updated: May 21, 2026

Study of the Functions and Activities of Neuronal K-Cl Co-Transporter KCC2 Using Western Blotting
10:08

Study of the Functions and Activities of Neuronal K-Cl Co-Transporter KCC2 Using Western Blotting

Published on: December 9, 2022

Isolation and Kv Channel Recordings in Murine Atrial and Ventricular Cardiomyocytes
11:33

Isolation and Kv Channel Recordings in Murine Atrial and Ventricular Cardiomyocytes

Published on: March 12, 2013

Mutagenesis and Functional Analysis of Ion Channels Heterologously Expressed in Mammalian Cells
15:28

Mutagenesis and Functional Analysis of Ion Channels Heterologously Expressed in Mammalian Cells

Published on: October 1, 2010

Area of Science:

  • Molecular Biology
  • Ion Channel Physiology
  • Biophysics

Background:

  • KCNQ3 homomeric channels exhibit low macroscopic currents compared to other KCNQ channels or KCNQ2/3 heteromers.
  • Both the C-terminus and pore region of KCNQ channels influence current amplitudes, with the pore region being more critical.

Purpose of the Study:

  • To confirm the critical role of the KCNQ3 pore region in determining KCNQ current amplitudes.
  • To investigate the structural mechanism behind reduced KCNQ3 channel currents caused by specific mutations.

Main Methods:

  • Site-directed mutagenesis of KCNQ3 and KCNQ2 channels at specific pore region positions.
  • Macroscopic current measurements and tetraethylammonium (TEA) sensitivity assays.
  • Total internal reflection fluorescence (TIRF) imaging for membrane protein expression analysis.
  • Homology modeling of KCNQ channel pore regions.

Main Results:

  • Mutations at position 312 in the KCNQ3 pore helix (I312E, I312K, I312R) drastically reduced both homomeric KCNQ3 and heteromeric KCNQ2/3 currents.
  • Mutations in analogous positions in KCNQ2 channels yielded similar reductions in current.
  • TIRF imaging showed minimal differences in membrane protein expression, indicating the current reduction is not due to expression levels.
  • Homology modeling suggests mutations cause pore helix-selectivity filter interactions that non-conductive conformation.

Conclusions:

  • The KCNQ3 pore region is critical for maintaining KCNQ channel current amplitudes.
  • Specific pore mutations disrupt channel function by inducing a non-conductive state of the selectivity filter.
  • These findings provide insights into the structural basis of KCNQ channel gating and ion permeation.