Related Experiment Video
Updated: Aug 6, 2026
10:19
Patch Clamp and Perfusion Techniques for Studying Ion Channels Expressed in Xenopus oocytes
Published on: January 10, 2011
Voltage- and Ca2+-activated potassium channels in Ca2+ store control Ca2+ release
Masayuki Yamashita1, Miho Sugioka, Yoichi Ogawa
1Department of Physiology I, Nara Medical University, Kashihara, Japan. yama@naramed-u.ac.jp
The FEBS Journal
|August 4, 2006
Summary
Calcium (Ca2+) release from stores is quantal. Big or maxi-K (BK) channels in the Ca2+ store regulate this release by closing as Ca2+ efflux decreases K+ influx, allowing for repetitive Ca2+ release.
Area of Science:
- Cellular Biology
- Ion Channel Function
- Calcium Signaling
Background:
- Calcium (Ca2+) release from intracellular stores exhibits quantal behavior, terminating after rapid efflux.
- The mechanism attenuating Ca2+ efflux, despite decreased luminal Ca2+, remains unclear.
Purpose of the Study:
- To elucidate the molecular mechanism controlling the quantal nature of Ca2+ release from stores.
- To identify the specific ion channels involved in regulating Ca2+ store release dynamics.
Main Methods:
- Utilized patch-clamp recordings from the nuclear envelope to study ion channel activity.
- Employed organelle-specific voltage-sensitive dyes (DiOC5(3)) to monitor luminal potential changes.
- Investigated the role of potassium channels in Ca2+ store release.
Main Results:
- Identified big or maxi-K (BK)-type potassium channels in the Ca2+ store as regulators of Ca2+ release.
- Demonstrated that BK channel closure, triggered by Ca2+ efflux, leads to lumen-negative potentials and suppresses further Ca2+ release.
- Showed that Ca2+ pumps and K+ influx regenerate BK channel activity, enabling repetitive Ca2+ release and bistable luminal potential oscillations.
Conclusions:
- Ca2+ efflux-induced closure of store BK channels attenuates Ca2+ release by reducing counter-influx of K+.
- BK channels act as a crucial feedback mechanism controlling the quantal release of Ca2+ from intracellular stores.
Related Concept Videos
01:19The 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.
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.
01:26Voltage-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...
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...
01:26Voltage-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...
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...
01:27Feedback Regulation of Calcium Concentration
Calcium is an essential signaling molecule required for various cellular functions. Calcium pumps and ion channels on cell and organellar membranes, such as those on the endoplasmic reticulum (ER), regulate calcium concentrations inside the cell. They remain closed, keeping the cytosolic calcium levels low at a resting state.
Various transmembrane receptors, such as G protein-coupled receptors (GPCRs), elicit a response to extracellular signals by increasing cytosolic calcium. Activated GPCRs...
Various transmembrane receptors, such as G protein-coupled receptors (GPCRs), elicit a response to extracellular signals by increasing cytosolic calcium. Activated GPCRs...
01:16Calmodulin-dependent Signaling
Calmodulin (CaM) is a calcium-binding protein in eukaryotes that controls various calcium-regulated cellular processes. It has four calcium-binding sites that bind calcium to form the calcium-calmodulin ( Ca2+-CaM) complex. GPCR stimulation increases the calcium levels in the cells that bind to CaM and induces a conformational change.
The Ca2+-CaM complex does not have enzymatic activity by itself. Instead, the complex binds downstream target proteins, including membrane proteins or enzymes,...
The Ca2+-CaM complex does not have enzymatic activity by itself. Instead, the complex binds downstream target proteins, including membrane proteins or enzymes,...
01:30Ligand-Gated Ion Channel Receptor: Gating Mechanism
Ligand-gated ion channels are transmembrane proteins that play a vital role in intercellular communication and functions of the nervous system. They allow the influx of ions across the membrane once the neurotransmitter binds, allowing the subsequent transmission of electrical excitation across the neurons. Other ligand-gated ion channels, like the γ-aminobutyric acid (GABA) receptor, permit anions like chloride into the cells on the binding of the GABA molecule. Their entry into the cell...