Niyogi, KK; Li, XP; Rosenberg, V; Jung, HS

The PsbS protein of photosystem II functions in the regulation of photosynthetic light harvesting. Along with a low thylakoid lumen pH and the presence of de-epoxidized xanthophylls, PsbS is necessary for photoprotective thermal dissipation (qE) of excess absorbed light energy in plants, measured as non-photochemical quenching of chlorophyll fluorescence. What is known about PsbS in relation to the hypothesis that this protein is the site of qE is reviewed here.