This family of uncharacterised proteins were first identified in the proteome of Treponema pallidum where they are assumed to be secreted proteins because of the presence of putative signal peptides. Homologues are known from other spirochaetes, Elusimicrobia and other bacteria.This family of putative ß-barrel proteins is still uncharacterised, but included in OMPdb since it belongs to the "Outer membrane ß-barrel protein superfamily" Pfam clan.