FeoB (773 amino acids in E. coli), a cytoplasmic membrane protein required for iron(II) update, is encoded in an operon with FeoA (75 amino acids), which is also required, and is regulated by Fur. There appear to be two copies in Archaeoglobus fulgidus and Clostridium acetobutylicum. [Transport and binding proteins, Cations and iron carrying compounds]
Jiyao W et al.(2023). "The conserved domain database in 2023.",