Patch-clamping of the inner mitochondrial membrane reveals a voltage-dependent ion channel

Nature ◽  
1987 ◽  
Vol 330 (6147) ◽  
pp. 498-500 ◽  
Author(s):  
M. Catia Sorgato ◽  
Bernhard U. Keller ◽  
Walter Stühmer
Keyword(s):  
Ion Channel ◽  
Mitochondrial Membrane ◽  
Patch Clamping ◽  
Inner Mitochondrial Membrane ◽  
Voltage Dependent

Calpeptin, not calpain, directly inhibits an ion channel of the inner mitochondrial membrane

PROTOPLASMA ◽  
2015 ◽  
Vol 253 (3) ◽  
pp. 835-843 ◽  
Author(s):  
Maria Derksen ◽  
Christian Vorwerk ◽  
Detlef Siemen
Keyword(s):  
Ion Channel ◽  
Mitochondrial Membrane ◽  
Inner Mitochondrial Membrane

scholarly journals Whole-GUV patch-clamping

2016 ◽  
Vol 114 (2) ◽  
pp. 328-333 ◽  
Author(s):  
Matthias Garten ◽  
Lars D. Mosgaard ◽  
Thomas Bornschlögl ◽  
Stéphane Dieudonné ◽  
Patricia Bassereau ◽  
...  
Keyword(s):  
Ion Transport ◽  
Ion Channel ◽  
High Resistance ◽  
Membrane Properties ◽  
Membrane Tension ◽  
Patch Clamping ◽  
Membrane Composition ◽  
Residual Solvent ◽  
Voltage Dependent

Studying how the membrane modulates ion channel and transporter activity is challenging because cells actively regulate membrane properties, whereas existing in vitro systems have limitations, such as residual solvent and unphysiologically high membrane tension. Cell-sized giant unilamellar vesicles (GUVs) would be ideal for in vitro electrophysiology, but efforts to measure the membrane current of intact GUVs have been unsuccessful. In this work, two challenges for obtaining the “whole-GUV” patch-clamp configuration were identified and resolved. First, unless the patch pipette and GUV pressures are precisely matched in the GUV-attached configuration, breaking the patch membrane also ruptures the GUV. Second, GUVs shrink irreversibly because the membrane/glass adhesion creating the high-resistance seal (>1 GΩ) continuously pulls membrane into the pipette. In contrast, for cell-derived giant plasma membrane vesicles (GPMVs), breaking the patch membrane allows the GPMV contents to passivate the pipette surface, thereby dynamically blocking membrane spreading in the whole-GMPV mode. To mimic this dynamic passivation mechanism, beta-casein was encapsulated into GUVs, yielding a stable, high-resistance, whole-GUV configuration for a range of membrane compositions. Specific membrane capacitance measurements confirmed that the membranes were truly solvent-free and that membrane tension could be controlled over a physiological range. Finally, the potential for ion transport studies was tested using the model ion channel, gramicidin, and voltage-clamp fluorometry measurements were performed with a voltage-dependent fluorophore/quencher pair. Whole-GUV patch-clamping allows ion transport and other voltage-dependent processes to be studied while controlling membrane composition, tension, and shape.

scholarly journals A Calcium Guard in the Outer Membrane: Is VDAC a Regulated Gatekeeper of Mitochondrial Calcium Uptake?

2021 ◽  
Vol 22 (2) ◽  
pp. 946
Author(s):  
Paulina Sander ◽  
Thomas Gudermann ◽  
Johann Schredelseker
Keyword(s):  
Mitochondrial Membrane ◽  
Calcium Release ◽  
Physiological Role ◽  
Mitochondrial Calcium ◽  
Inner Mitochondrial Membrane ◽  
New Era ◽  
Voltage Dependent ◽  
Common Opinion ◽  
Long Time ◽  
The Individual

Already in the early 1960s, researchers noted the potential of mitochondria to take up large amounts of Ca2+. However, the physiological role and the molecular identity of the mitochondrial Ca2+ uptake mechanisms remained elusive for a long time. The identification of the individual components of the mitochondrial calcium uniporter complex (MCUC) in the inner mitochondrial membrane in 2011 started a new era of research on mitochondrial Ca2+ uptake. Today, many studies investigate mitochondrial Ca2+ uptake with a strong focus on function, regulation, and localization of the MCUC. However, on its way into mitochondria Ca2+ has to pass two membranes, and the first barrier before even reaching the MCUC is the outer mitochondrial membrane (OMM). The common opinion is that the OMM is freely permeable to Ca2+. This idea is supported by the presence of a high density of voltage-dependent anion channels (VDACs) in the OMM, forming large Ca2+ permeable pores. However, several reports challenge this idea and describe VDAC as a regulated Ca2+ channel. In line with this idea is the notion that its Ca2+ selectivity depends on the open state of the channel, and its gating behavior can be modified by interaction with partner proteins, metabolites, or small synthetic molecules. Furthermore, mitochondrial Ca2+ uptake is controlled by the localization of VDAC through scaffolding proteins, which anchor VDAC to ER/SR calcium release channels. This review will discuss the possibility that VDAC serves as a physiological regulator of mitochondrial Ca2+ uptake in the OMM.

scholarly journals Recombinant expression of the voltage-dependent anion channel enhances the transfer of Ca2+ microdomains to mitochondria

2002 ◽  
Vol 159 (4) ◽  
pp. 613-624 ◽  
Author(s):  
Elena Rapizzi ◽  
Paolo Pinton ◽  
György Szabadkai ◽  
Mariusz R. Wieckowski ◽  
Grégoire Vandecasteele ◽  
...  
Keyword(s):  
Mitochondrial Membrane ◽  
High Speed ◽  
Recombinant Expression ◽  
Anion Channel ◽  
Fast Diffusion ◽  
Inner Mitochondrial Membrane ◽  
Voltage Dependent Anion Channel ◽  
High Speed Imaging ◽  
Physiological Relevance ◽  
Voltage Dependent

Although the physiological relevance of mitochondrial Ca2+ homeostasis is widely accepted, no information is yet available on the molecular identity of the proteins involved in this process. Here we analyzed the role of the voltage-dependent anion channel (VDAC) of the outer mitochondrial membrane in the transmission of Ca2+ signals between the ER and mitochondria by measuring cytosolic and organelle [Ca2+] with targeted aequorins and Ca2+-sensitive GFPs. In HeLa cells and skeletal myotubes, the transient expression of VDAC enhanced the amplitude of the agonist-dependent increases in mitochondrial matrix Ca2+ concentration by allowing the fast diffusion of Ca2+ from ER release sites to the inner mitochondrial membrane. Indeed, high speed imaging of mitochondrial and cytosolic [Ca2+] changes showed that the delay between the rises occurring in the two compartments is significantly shorter in VDAC-overexpressing cells. As to the functional consequences, VDAC-overexpressing cells are more susceptible to ceramide-induced cell death, thus confirming that mitochondrial Ca2+ uptake plays a key role in the process of apoptosis. These results reveal a novel function for the widely expressed VDAC channel, identifying it as a molecular component of the routes for Ca2+ transport across the mitochondrial membranes.

Modulation of the calcium-activated BK-channel of the inner mitochondrial membrane by hypoxia

2007 ◽  
Vol 34 (S 2) ◽  
Author(s):  
D Siemen ◽  
Y Cheng ◽  
X Gu ◽  
P Bednarczyk ◽  
GG Haddad ◽  
...  
Keyword(s):  
Mitochondrial Membrane ◽  
Bk Channel ◽  
Inner Mitochondrial Membrane

The Efects of Spaceflight on Mitochondria in Human Lymphocytes (Jurkat).

1999 ◽  
Vol 5 (S2) ◽  
pp. 1118-1119
Author(s):  
Heide Schatten ◽  
Marian Lewis
Keyword(s):  
Mitochondrial Membrane ◽  
Space Shuttle ◽  
Human Lymphocytes ◽  
Jurkat Cells ◽  
Apoptotic Bodies ◽  
Inner Mitochondrial Membrane ◽  
Mitochondrial Alterations ◽  
Mitochondrial Volume ◽  
Number Of Cells ◽  
Related Increase

Spaceflight induced mitochondrial alterations have been reported for muscle and may be associated with altered physiological functions in space. Mitochondrial alterations are also indicative of preapoptotic events which are seen in greater amounts in cells exposed to spaceflight when compared with cells cultured at 1 g. Preapoptotic mitochondrial changes include alterations of processes at the inner mitochondrial membrane and can result in changes in mitochondrial volume. Higher amounts of oxidative stress during space flight may be one of the causes for changes which lead to apoptosis. Jurkat cells flown on the STS-76 space shuttle mission showed an increase in the number of cells with apoptotic bodies early in the mission and a time-dependent, microgravity-related increase in the Fas/APO-1 cell death factor. Here we investigated the morphology of mitochondria in Jurkat cells exposed to spaceflight during the STS-76 mission.

Sign in / Sign up

Export Citation Format

Share Document