Balance of power: a view of the mechanism of photosynthetic state transitions

Photosynthesis in plants involves photosystem I and photosystem II, both of which use light energy to drive redox processes. Plants can balance the di stribution of absorbed light energy between the two photosystems, When phot osystem II is favoured, a mobile pool of light harvesting complex II moves from photosystem II to photosystem I. This short-term and reversible redist ribution is known as a state transition, It is associated with changes in t he phosphorylation of light harvesting complex II but the regulation is com plex. Redistribution of energy during state transitions depends on an alter ed binding equilibrium between the light harvesting complex Il-photosystem II and light harvesting complex Il-photosystem I complexes.