Required for efficient pedestal formation in host epithelial cells during infection. Acts as an intermediate between Tir (via host BAIAP2) and host WASL/N-WASP. Directly binds and activates WASL/N-WASP, which stimulates actin polymerization and leads to the formation of actin pedestals at the sites of bacterial adhesion. Interacts with host BAIAP2 and host WASL/N-WASP. Can also interact with host proteins BAIAP2L1 and WAS/WASP. Secreted via the type III secretion system (TTSS) (PubMed:15527496, PubMed:15296718). In host cells, localizes to the tip of the actin pedestal (PubMed:15527496, PubMed:15296718). The N-terminal 21 amino acids are necessary and sufficient for translocation into the host cell. The C-terminal region, composed of several highly conserved proline-rich repeats, interacts with the SH3 domain of BAIAP2 and BAIAP2L1, and the GTPase binding domain (GBD) of WASL/N-WASP and WAS/WASP. The N-terminal translocation signal and two proline-rich repeats are sufficient for triggering actin polymerization, but each additional repeat gives higher activity. Mutants show dramatic reduction in the efficiency of pedestal formation and in the intensity of the residual pedestals that are formed. Belongs to the EspF(U)/TccP family.