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. 2010 Feb 8;1(2):94–99. doi: 10.4161/gmic.1.2.11437

Figure 1.

Figure 1

Model for host-cell signalling induced by EPEC Tir. Tir is an effector protein of EPEC, which is injected into host cells by a type-III secretion system (T3SS). Translocated Tir is rapidly inserted into the host cell membrane where interaction with the bacterial surface protein Intimin triggers signalling leading to disease-related events. Tir membrane insertion results in a hairpin-like structure of the protein and correlates with multiple phosphorylation events at indicated serine/tyrosine residues. While the tyrosine residues Y-454 and Y-474 can be phosphorylated by Fyn, Tec and/or Abl kinases, the serine residues S-434 and S-463 are phosphorylated by PKA. Injected Tir has at least 10 interacting host cell proteins as indicated. The induced downstream signal cascades can be classified in three categories: (A) phosphorylation-independent, (B) dependent on Tir tyrosine phosphorylation, and (C) dependent on Tir serine phosphorylation. For more details see text.