Compare trasnferrin, ferritin, and lactoferrin?
All of these are transport proteins for iron.
Transferrin transports protein to cells.
Ferritin stores excess iron in the liver.
Lactoferrin has a greater affinity for iron, and is used when certain bacteria come in and steal iron from transferrin. (Ex: Staphylococcus aureus and its iron-stealing proteins called siderophores)