A Brief History of Ferritin, an Ancient and Versatile Protein

Ferritin, a highly conserved iron storage protein, is among the earliest proteins that have been purified, named, and characterized due to its unique properties that continue to captivate researchers. Ferritin is composed of 24 subunits that form an almost spherical shell delimiting a cavity where thousands of iron atoms can be stored in a nontoxic ferric form, thereby preventing cytosolic iron from catalyzing oxidative stress. Mitochondrial and extracellular ferritin have also been described and characterized, with the latter being associated with several signaling functions. In addition, serum ferritin serves as a reliable indicator of both iron stores and inflammatory conditions. First identified and purified through crystallization in 1937, ferritin has since drawn significant attention for its critical role in iron metabolism and regulation. Its unique structural features have recently been exploited for many diverse biological and technological applications. To date, more than 40,000 publications have explored this remarkable protein. Here, we present a historical overview, tracing its journey from discovery to current applications and highlighting the evolution of biochemical techniques developed for its structure-function characterization over the past eight decades.