Related Experiment Video
Updated: Jun 20, 2026
10:27
Measuring Trans-Plasma Membrane Electron Transport by C2C12 Myotubes
Published on: May 4, 2018
Transplasma membrane electron transport comes in two flavors
Darius J R Lane1, Alfons Lawen
1Department of Biochemistry and Molecular Biology, School of Biomedical Sciences, Monash University, VIC 3800, Australia.
Biofactors (Oxford, England)
|September 8, 2009
Summary
Cells utilize transplasma membrane electron transfer (tPMET) for nutrient uptake. A novel ascorbate/dehydroascorbate cycle facilitates non-transferrin-bound iron (NTBI) reduction and uptake in K562 cells.
Area of Science:
- Cellular Biology
- Biochemistry
- Physiology
Background:
- Cells possess transplasma membrane electron transfer (tPMET) systems for extracellular reduction.
- Mammalian tPMET classically involves NAD(P)H- and NADH-dependent systems.
- NADH-dependent systems are implicated in non-transferrin-bound iron (NTBI) reduction and uptake.
Purpose of the Study:
- To investigate the role of transplasma membrane ascorbate/dehydroascorbate cycling in NTBI reduction and uptake.
- To propose this cycling system as a novel form of tPMET.
- To distinguish between enzyme-mediated and metabolite-mediated tPMET.
Main Methods:
- Utilized human erythroleukemia (K562) cells.
- Investigated the ascorbate/dehydroascorbate cycling mechanism.
- Analyzed NTBI reduction and uptake processes.
Main Results:
- Transplasma membrane ascorbate/dehydroascorbate cycling promotes NTBI reduction and uptake in K562 cells.
- This system involves dehydroascorbate import, intracellular reduction, ascorbate export, and iron uptake.
- The cycling system functions as a novel tPMET mechanism distinct from classical enzyme-mediated systems.
Conclusions:
- Transplasma membrane electron transfer occurs via two distinct mechanisms: enzyme-mediated and metabolite shuttling/cycling.
- The ascorbate/dehydroascorbate cycle represents a novel, non-enzymatic tPMET pathway.
- This finding expands the understanding of cellular electron transfer and nutrient acquisition.
More Related Videos
Related Concept Videos
01:29Electron Transport Chain Components
The electron transport chain (ETC) is a crucial metabolic pathway that facilitates energy conversion in prokaryotic and eukaryotic cells. In eukaryotes, the ETC comprises four membrane-associated protein complexes in the inner mitochondrial membrane. In prokaryotes, the ETC in the plasma membrane can vary in composition, with fewer or different complexes depending on the organism and environmental conditions. These complexes transfer electrons from electron donors, such as NADH and FADH2, to...
01:19Membrane Asymmetry Regulating Transporters
Enzymes like flippase, floppase, and scramblase transfer phospholipids from one layer to another in the membrane, thereby affecting membrane asymmetry.
Flippase
Eukaryotic flippases are type-IV P-type ATPases or P4-ATPases belonging to P-type ATPase family proteins that are membrane-bound pumps involved in the ATP-mediated transport of ions and molecules across the membrane. Flippases flip specific phospholipids from the outer to the inner leaflet of a membrane. All P4-ATPases have one...
Flippase
Eukaryotic flippases are type-IV P-type ATPases or P4-ATPases belonging to P-type ATPase family proteins that are membrane-bound pumps involved in the ATP-mediated transport of ions and molecules across the membrane. Flippases flip specific phospholipids from the outer to the inner leaflet of a membrane. All P4-ATPases have one...
01:28Electron Transport Chains
The final stage of cellular respiration is oxidative phosphorylation that consists of two steps: the electron transport chain and chemiosmosis. The electron transport chain is a set of proteins found in the inner mitochondrial membrane in eukaryotic cells. Its primary function is to establish a proton gradient that can be used during chemiosmosis to produce ATP and generate electron carriers, such as NAD+ and FAD, that are used in glycolysis and the citric acid cycle.
The ETC is comprised of...
The ETC is comprised of...
01:29Insertion of Multi-pass Transmembrane Proteins in the RER
The rough ER membrane synthesizes, assembles, and embeds transmembrane proteins in diverse topologies. These proteins function as transporters or channels and can remain in the ER membrane or are sent to the Golgi complex, lysosome, and cell membrane.
The multipass transmembrane proteins are the type IV integral membrane proteins with multiple topogenic sequences determining their spatial arrangement in the ER membrane. Nearly all multipass proteins lack a cleavable signal sequence and use...
The multipass transmembrane proteins are the type IV integral membrane proteins with multiple topogenic sequences determining their spatial arrangement in the ER membrane. Nearly all multipass proteins lack a cleavable signal sequence and use...
01:19Translocation of Proteins into the Mitochondria
Mitochondrial precursors are translocated to the internal subcompartments via independent mechanisms involving distinct protein machineries called translocases.
Sorting of outer membrane proteins:
Mitochondrial outer membrane proteins are of two types: the transmembrane, beta-barrel porins, and the membrane-anchored, alpha-helical proteins. Beta-barrel porin precursors are translocated by the TOM complex and inserted into the outer mitochondrial membrane by the SAM complex. In contrast,...
Sorting of outer membrane proteins:
Mitochondrial outer membrane proteins are of two types: the transmembrane, beta-barrel porins, and the membrane-anchored, alpha-helical proteins. Beta-barrel porin precursors are translocated by the TOM complex and inserted into the outer mitochondrial membrane by the SAM complex. In contrast,...
01:34Protein Transport into the Inner Mitochondrial Membrane
Nuclear encoded mitochondrial precursors are imported to the inner membrane in a multistep process involving two separate translocons, TIM22 and TIM23. TIM23 is a cation-selective pore that remains closed by the N terminal segment of the protein. Negative charges on the TIM23 act as a receptor for the incoming precursor, pulling the positively charged matrix-targeting sequence for peptide insertion and translocation.
Transport of mitochondrial precursors across the TIM23 channel is driven by...
Transport of mitochondrial precursors across the TIM23 channel is driven by...