Figure 1.

Effectors crossing the host–pathogen interface. (A) Oomycete plant pathogens secrete RXLR–dEER effector proteins from haustoria into the extrahaustorial matrix (em). How these effectors cross the plant plasma membrane (ppm) to reach the host cell cytoplasm is unknown. (B) Bacterial pathogens exploit the Type III secretion system (T3SS) to inject effectors into the host cell cytoplasm. T3SS is a pathogen-derived multi-protein needle-like structure that penetrates the plant cell wall (pcw) and the plasma membrane. (C) Malaria parasites (Plasmodium spp.) invade red blood cells and secrete effector proteins into the parasitophorous vacuole (pv). PEXEL effectors are translocated to the red blood cell cytoplasm (rbcc) via a pathogen-derived translocon complex (PTEX), which resides in the parasitophorous vacuole membrane (pvm). Effectors are shown in different colored bars [in (A,C)] and hexagons [in (B)]. In the colored bars the red box is the signal peptide (SP) and the blue box the RXLR or RXLX^E/Q motif.