Seems to act as a signaling molecule involved in the maintenance of iron homeostasis. Seems to be required in conjunction with HFE to regulate both intestinal iron absorption and iron storage in macrophages (By similarity). Has very strong antibacterial activity against the marine Gram-negative bacteria V.alginolyticus (MIC=24 uM), V.fluvialis, V.harveyis (MIC=12 uM) and V.parahaemolyticus (MIC=6 uM). Has antibacterial activity against the Gram-negative bacteria A.hydrophila (MIC=6 uM), E.coli (MIC=24 uM), and E.coli BL21(DE3)plysS (MIC=6 uM), and the Gram-positive bacteria B.cereus (MIC=24 uM), B.subtilis (MIC=6 uM), C.glutamicum (MIC=3 uM), M.luteus (MIC=3 uM), M.lysodeikticus, S.aureus (MIC=6 uM) and S.epidermis (MIC=12 uM). Possesses antifungal activity against A.niger (MIC=24 uM), F.graminearum (MIC24 uM) and F.solani (MIC=24 uM), but lacks antifungal activity against the yeasts P.pastoris GS115 and C.albicans. Monomer. Expressed in all tissues tested, with highest levels of expression in kidney and lowest levels in liver. Intra-peritoneal injection of lipopolysaccharide results in increased expression in heart, spleen and stomach, but not in kidney or liver. Belongs to the hepcidin family.