InterPro domain: IPR044130

Fet3 is a multicopper-containing glycoprotein localised to the yeast plasma membrane that catalyses the oxidation of Fe(II) to Fe(III). The periplasmic produced Fe(III) is transferred to the permease Ftr1 for import into the cytosol. The four copper ions are inserted post-translationally and are essential for catalytic activity, thus linking copper and iron homeostasis [ 1 , 2 ].

Like other related multicopper oxidases (MCOs), Fet3 is composed of three cupredoxin domains that include one mononuclear and one trinuclear copper centre. The copper ions are bound in several sites: Type 1, Type 2, and/or Type 3. The ensemble of types 2 and 3 copper is called a trinuclear cluster. MCOs oxidize their substrate by accepting electrons at a mononuclear copper centre and transferring them to the active site trinuclear copper centre. The cupredoxin domain 2 of 3-domain MCOs has lost the ability to bind copper [ 3 ].

This entry represents the the second Cupredoxin domain of Fet3. This domain can also be found in Fet5, Gmc1 from budding yeasts and Fio1 from fission yeasts [ 3 ].

1. The copper-iron connection in biology: structure of the metallo-oxidase Fet3p. Proc. Natl. Acad. Sci. U.S.A. 102, 15459-64
2. Evidence for iron channeling in the Fet3p-Ftr1p high-affinity iron uptake complex in the yeast plasma membrane. Biochemistry 45, 6317-27
3. An oxidase-permease-based iron transport system in Schizosaccharomyces pombe and its expression in Saccharomyces cerevisiae. J. Biol. Chem. 272, 401-5