Iron transport in Saccharomyces cerevisiae

The ferrireductases are able to reduce other metals besides iron, and FREl has been shown to be important for copper transport [17, 18]. A mammalian counterpart to the ferrireductase has not been described, although ferrireductase activity has been observed in numerous tissues [19-23]. Interestingly, the ferrireductases of yeast show significant homology to the NADPH oxidoreductase which is a component of the enzyme complex responsible for the oxidative burst of the immune system [24]. In addition, within the yeast genome there are also five other ferrireductase-like genes with unknown function. 

The ferrous iron produced by the ferrireductases can be transported through either a high affinity or a low afiinity iron transport system. The low affinity iron transport system has a Kta for iron of 30 pM and transports other metals in addition to iron including the potentially toxic metals cadmium and cobalt [25]. The FET4 

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