This is a family of effector proteins which are secreted by the type III secretion system [1,2]. The precise function of this family is unknown.

1: Identification of Chlamydia trachomatis CT621, a protein delivered through the type III secretion system to the host cell cytoplasm and nucleus. Hobolt-Pedersen AS, Christiansen G, Timmerman E, Gevaert K, Birkelund S; FEMS Immunol Med Microbiol. 2009;57:46-58. PMID:19682078

2: Identification of a family of effectors secreted by the type III secretion system that are conserved in pathogenic Chlamydiae. Muschiol S, Boncompain G, Vromman F, Dehoux P, Normark S, Henriques-Normark B, Subtil A; Infect Immun. 2011;79:571-580. PMID:21078856