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In essence, the Goldman formula expresses the membrane potential as a weighted average of the reversal potentials for the individual ion types, weighted by permeability. (Although the membrane potential changes about 100 mV during an action potential, the concentrations of ions inside and outside the cell do not change significantly.
[1] [2] There is debate as to whether or not this channel is expressed in the cell surface membrane. [3] [4] [5] This major protein of the outer mitochondrial membrane of eukaryotes forms a voltage-dependent anion-selective channel (VDAC) that behaves as a general diffusion pore for small hydrophilic molecules.
Mitochondrial uncoupling protein 3 (UCP3) is a members of the larger family of mitochondrial anion carrier proteins (MACP). UCPs facilitate the transfer of anions from the inner to the outer mitochondrial membrane and transfer of protons from the outer to the inner mitochondrial membrane, reducing the mitochondrial membrane potential in mammalian cells.
The membrane potential is necessary for both insertion of the precursor into the carrier translocase and lateral release of the protein into the lipid phase of the inner mitochondrial membrane, which completes protein translocation. However this membrane potential-dependent process takes place in absence of ATP-driven machinery. [8]
VDAC1's function in calcium ion transport has also been linked to neurodegenerative diseases. In PD, VDAC1 increases calcium ion levels within the mitochondria, resulting in increased mitochondrial permeability, disrupted mitochondrial membrane potential, elevated ROS production, cell death, and neuronal degeneration. [12]
Mitochondria present in all cells in the human body require a resting membrane potential of the inner mitochondrial membrane to synthesize adenosine triphosphate (ATP). This membrane polarity is established through a series of proton pumps transporting hydrogen ions into the mitochondrion.
Mitochondrial outer membrane permeabilization (MOMP), also known as the mitochondrial outer membrane permeability, is one of two ways apoptosis (a type of programmed cell death) can be activated. [1] It is part of the intrinsic pathway of apoptosis, also known as the mitochondrial pathway. MOMP is known as the point of no return in apoptosis.
The grey area is the inner mitochondrial membrane. Q represents the ubiquinone form of CoQ, and QH 2 represents the ubiquinol ( dihydroxyquinone ) form. The Q cycle (named for quinol ) describes a series of sequential oxidation and reduction of the lipophilic electron carrier Coenzyme Q (CoQ) between the ubiquinol and ubiquinone forms.