A @MT06878@-bound complex in plants and photosynthetic bacteria, responsible for light-harvesting and primary @E02011@. Comprises light-harvesting pigments such as chlorophyll; a primary electron-transfer centre, and secondary electron carriers. In green plant @P04655@, Photosystem I transfers electrons from plastocyanin to a [2Fe-2S] @FT06771@, and contains @IT06780@. Photosystem II transfers electrons from the oxygen-evolving complex to plastoquinone, and contains an iron centre.