This family consists of several RTX iron-regulated FrpC proteins which appear to be found exclusively in Neisseria meningitidis. FrpC has been shown to be related to the RTX family of bacterial cytotoxins. FrpC is found in the meningococcal outer membrane. The function of this family is unknown although it is thought to be a virulence factor [1].

1: Neisseria meningitidis RTX proteins are not required for virulence in infant rats. Forman S, Linhartova I, Osicka R, Nassif X, Sebo P, Pelicic V; Infect Immun 2003;71:2253-2257. PMID:12654851