Ferredoxins are a family or proteins that contain cysteine-coordinated iron-sulfur clusters and function in facilitating electron transport in biological redox reactions. Plant-type ferredoxins are found in plant choloroplasts and transport electrons in the photosynthetic electron transport chain. The adrenal ferredoxin (Ferredoxin-1) in humans participates in mitochondrial electorn transfer and also with the synthesis of thyroid hormones. Other human proteins of the Ferredoxin family include: AOX1; FDX1; FDX1L; NDUFS1; SDHB; XDH; ABCE1; DPYD; NDUFS8.