Hepcidin is a 25 amino acid peptide produced by the liver. Hepcidin structure was determined by nuclear magnetic resonance. The peptide forms a bent hairpin stabilized by four disulfide bonds (yellow).

Hepcidin exerts its activity by binding to its receptor ferroportin. Ferroportin is a channel which exports iron from cells into plasma (panel A: cells expressing ferroportin-GFP fusion protein). When hepcidin binds to ferroportin, it causes ferroportin to be internalized and degraded (B). Internalized ferroportin cannot export iron out of the cells.