Salmonella invasion protein A is an actin-binding protein that contributes to host cytoskeletal rearrangements by stimulating actin polymerisation and counteracting F-actin destabilising proteins. Members of this family possess an all-helical fold consisting of eight alpha-helices arranged so that six long, amphipathic helices form a compact fold that surrounds a final, predominantly hydrophobic helix in the middle of the molecule [1].

1: A common structural motif in the binding of virulence factors to bacterial secretion chaperones. Lilic M, Vujanac M, Stebbins CE; Mol Cell. 2006;21:653-664. PMID:16507363