This is a family of transport proteins. Members of this family include a protein responsible for the secretion of the ferric chelator, enterobactin [1], and a protein involved in antibiotic resistance [2].

1: Export of the siderophore enterobactin in Escherichia coli: involvement of a 43 kDa membrane exporter. Furrer JL, Sanders DN, Hook-Barnard IG, McIntosh MA; Mol Microbiol. 2002;44:1225-1234. PMID:12068807

2: The cme gene of Clostridium difficile confers multidrug resistance in Enterococcus faecalis. Lebel S, Bouttier S, Lambert T; FEMS Microbiol Lett. 2004;238:93-100. PMID:15336408