Multifunctional protein that is required for efficient pedestal formation in host epithelial cells during infection. The extracellular region acts as a receptor for bacterial intimin, allowing the bacterium to attach tightly to the host-cell surface. Simultaneously, the intracellular region initiates a signaling cascade in the host cell, which leads to actin polymerization and formation of actin pedestals at the sites of bacterial adhesion. In strain E2348/69, acts mainly via the host adaptor proteins NCK1 and NCK2. Once clustered and phosphorylated at Tyr-474, Tir binds to NCK proteins, which in turn bind and activate host WASL/N-WASP, leading to actin polymerization. Can also trigger an inefficient, NCK-independent pedestal formation. This pathway involves phosphorylation of Tyr-454 and probably a putative host adaptor. Acts also via direct binding to the host cytoskeletal protein alpha-actinin in a NCK- and phosphotyrosine-independent manner. This interaction may stabilize the pedestal, but is not essential for its formation. Interacts with intimin. Interacts with host proteins NCK1, NCK2, alpha-actinin and BAIAP2. Secreted via the type III secretion system (TTSS). Released into the host cytoplasm via TTSS and then independently inserts into the plasma membrane from a cytoplasmic location. In host cells, localizes to the tip of the actin pedestal. The intracellular N-terminal region interacts with host alpha-actinin and is not required for pedestal formation. The central extracellular region (amino acids 277-332) is involved in bacterial intimin binding. The intracellular C-terminal region binds to host NCK. Phosphorylated on Tyr-474 by host kinases. Tyr-454 can also be phosphorylated, although at lower efficiency. Phosphorylation is stimulated by clustering of Tir by intimin. Belongs to the Tir receptor family.