A new model for the architecture of the TgMIC4–1–6 complex. A schematic representation of a model for the TgMIC4–1–6 complex illustrating the relative location of the domains and host cell-binding sites. The sialic acid-containing receptor(s) are shown as pink space-filling spheres. Colour code: yellow, apple domains; purple, microneme adhesive repeat (MAR) domain; orange, galectin-like domain (GLD); green and blue, second and third epidermal growth factor-like (EGF) domains; grey, transmembrane (TM); and red cylinder, acidic region. The six apple domains of TgMIC4 are represented as yellow circles, as no structural information is available. MIC, microneme protein.