Ferredoxins are iron-sulfur proteins that transfer electrons in a wide variety of metabolic reactions (Probable). Mediates alternative electron partitioning in conditions of acceptor limitation at photosystem I (By similarity). Binds 1 [2Fe-2S] cluster. Slightly up-regulated in response to acceptor limitation at photosystem I (PSI) in plants lacking of photosynthetic [2Fe-2S] ferredoxin (Fd). Belongs to the 2Fe2S plant-type ferredoxin family.