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 (By similarity). Interacts with host BAIAP2 and host WASL/N-WASP. Can also interact with host proteins BAIAP2L1 and WAS/WASP (By similarity). Secreted via the type III secretion system (TTSS). In host cells, localizes to the tip of the actin pedestal (By similarity). 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 (By similarity). Belongs to the EspF(U)/TccP family.