Plastoquinone (PQ) is a terpenoid-quinone (meroterpenoid) molecule involved in the electron transport chain in the light-dependent reactions of photosynthesis.

[1] The benzoquinone and isoprenyl units are both nonpolar, anchoring the molecule within the inner section of a lipid bilayer, where the hydrophobic tails are usually found.

[2] Plastoquinone is reduced when it accepts two electrons from photosystem II and two hydrogen cations (H+) from the stroma of the chloroplast, thereby forming plastoquinol (PQH2).

[2] The cytochrome b6f protein complex catalyzes the electron transfer between plastoquinone and plastocyanin, but also transports the two protons into the lumen of thylakoid discs.

[2] There are additional plastoquinone binding sites within photosystem II (QC and possibly QD), but their function and/or existence have not been fully elucidated.

[10] SkQR1 and SkQ1 have also been proposed as a possible way to treat brain issues like Alzheimer's due to their ability to potentially fix damages caused by amyloid beta.