Escherichia coli has an iron(II) transport system (feo) which may make an important contribution to the iron supply of the cell under anaerobic conditions. FeoB has been identified as part of this transport system. FeoB is a large 700-800 amino acid integral membrane protein. The N-terminus has been previously erroneously described as being ATP-binding. Recent work shows that it is similar to eukaryotic G-proteins and that it is a GTPase.