Component of Salmonella pathogenicity island 2 (SPI-2) type III secretion system, required for secretion of some type III-secreted effectors including the SpvB exotoxin. 100-fold reduction in cytopathic effects in human monocyte-derived macrophages, loss of polymerization of G- to F-actin in macrophages. Belongs to the FHIPEP (flagella/HR/invasion proteins export pore) family.