This family consists of some not yet well-characterized outer membrane proteins. The prototype of the family, YfaZ of Escherichia coli, was initially predicted to be a transmembrane ß-barrel and its localization to the outer membrane was confirmed by experimental methods. Its biological function however remains unclear. Homologs are also found in other genera, such as Shigella, Salmonella, Yersinia, Erwinia and Shewanella.