Electron and proton transport across the plasma membrane

Area of Science:

• Cellular Physiology
• Biochemistry
• Plant Biology
• Animal Biology

Background:

• Transplasma membrane electron transport (TET) is observed in both plant and animal cells, leading to proton release.
• The precise components and mechanisms of TET and its proton release activation are not fully understood.
• Plasma membranes contain potential electron transport components like cytochromes, flavins, iron, and quinones.

Purpose of the Study:

• To investigate the role of transplasma membrane electron transport in proton release.
• To explore the components and mechanisms involved in activating proton release via electron transport.
• To understand the physiological implications of redox-induced proton release in plant and animal cells.

Main Methods:

• Utilizing reduced pyridine nucleotides as substrates for plasma membrane dehydrogenases.
• Employing impermeable oxidants (e.g., ferricyanide) and natural electron acceptors (e.g., oxygen, ferric chelates, ferric transferrin) to probe TET activity.
• Investigating the effects of light (red/blue) in plants and specific ions (sodium) and inhibitors (amilorides) in animal cells on proton release.

Main Results:

• TET activates proton release in both plant and animal cells.
• Oxygen, ferric chelates, and ferric transferrin serve as natural electron acceptors, while artificial oxidants also probe activity.
• In animal cells, TET appears to activate the Na+/H+ antiport; in plants, H+ ATPase activation contributes to proton release.
• Red/blue light stimulates TET and proton release in plants; specific inhibitors block this process.

Conclusions:

• Transplasma membrane electron transport is a significant pathway for proton release in diverse cell types.
• Redox-induced proton release influences cellular pH and is linked to cell growth stimulation.
• While components are present, the exact participation of cytochromes, flavins, and iron in TET requires further elucidation.