Transthyretin is a serum protein synthesized in the liver, which transports thyroxine and retinol binding protein, but has no role in iron metabolism.
Proteins involved in iron metabolism:
Ceruloplasmin : Required for oxidation of Fe2+ to Fe3+
DMT1
Ferrireductase
Ferritin : Forms hemosiderin granules when there is excess iron
Ferroportin
Heme transporter
Hemojuvelin
Hepcidin: Lowers plasma iron levels, while deficiency causes iron overload
Hephaestin
HFE
Iron responsive element-binding protein
Transferrin: Along with transferrin receptors 1 and 2