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The iron exporter Ferroportin1 (Fnp1 or IREG1)

Ferroportin (IREG1) of Mus musculus

The probable chloroplast Fe transporter, Mar1 (Conte et al., 2009)

Mar1 of Arabidopsis thaliana (Q8W4E7)

Ferroportin1 or Iron-regulated protein1, 9FPN1, IREG1, ATIREG1; exports Fe2+, Co2+ and Ni2+ (Morrissey et al., 2009)

FPN1 of Arabidopsis thaliana (O80905)

Solute carrier family 40 member 1 (Ferroportin-1; FPN1) (Iron-regulated transporter 1).  Transports iron, cobalt, zinc and manganese and maybe copper (Madejczyk and Ballatori 2012).  Regulated by its inhibitor, the processed liver antimicrobial peptide, hepcidin (TC# 8.A.37.1.2).  Tryptophan 42, a hemochromatosis type 4 disease residue, plays a role in iron export and iron homeostasis as well as hepcidin binding (Le Gac et al. 2013).  This protein has been modeled using the MSF EmrD of E. coli (TC# 2.A.1.2.9) (Le Gac et al. 2013). Defects can be corrected by adding the small molecule, hinokitiol (Cioffi et al. 2015; Grillo et al. 2017). The R178Q mutation is a recurrent cause of hemochromatosis and is associated with a novel pathogenic mechanism (Ka et al. 2018).

FPN1 or SLC40A1 of Homo sapiens

Ferroportin of 565 aas and 12 TMSs.

Fpn of Chlorella variabilis (Green alga)

Uncharacterized ferroportin homolog of 560 aas and 14 TMSs, with two extra TMSs between the two 6 TMS repeat units.

UP of Peronospora effusa

Ferroportin (Fpn) of 562 aas and 12 TMSs (Rafiee et al. 2012).

Fpn of Danio rerio (zebrafish)

Ferroportin of 440 aas and 12 TMSs. Transports Fe2+, Co2+, Mn2+ and Ni2+. The 3-d structures in both the inward and outward facing orientations have been determined, showing similarities to those of MFS permeases (Taniguchi et al. 2015). The Fpn family is a member of the MFS. Fpn-mediated iron efflux is stimulated by extracellular Ca2+ in the physiological range, even though  Ca2+ is not transported. Deshpande et al. 2018 determined the crystal structure of Ca2+-bound BbFpn (TC# 2.A.100.2.1), and found that Ca2+ is a cofactor that facilitates a conformational change critical to the transport cycle. They also identified a substrate pocket accommodating a divalent transition metal complexed with a chelator. These findings support a model of iron export by Fpn and suggest a link between plasma calcium and iron homeostasis (Deshpande et al. 2018).

Ferroportin of Bdellovibrio bacteriovorus

Uncharacterized Ferroporin homologue of 592 aas and 12 putative TMSs.

UP of Acytostelium subglobosum