SptP is a virulence effector protein of Salmonella that is involved in bacterial invasion into a host cell. For effective secretion, SptP forms a complex with SptP-specific chaperone SicP through its chaperone-binding domain, residues 35-139. Here, we suggest the possibility that residues 106-136 of SptP are important for complex formation with SicP by in vitro reconstitution experiments.