Figure 4. Substrate translocation pathway.

a, Cα-trace of the translocation pathway region of ABCG2_EQ-E₁S. Residues lining the substrate-binding cavity are shown as sticks, bound E₁S has been omitted for clarity. The dashed line shows the distance between the two F439 residues that stack against bound E₁S. b, Vertical slice through a surface representation of ABCG2_EQ-E₁S, with bound E₁S shown as pink spheres and the two cavities and plug region labeled. On the right panel, 90° rotation of the structure revealing the fit of E₁S in the substrate-binding cavity, as viewed from the cytoplasm. The NBDs have been removed for clarity. c,d Similar to a,b but of the ABCG2_EQ-ATP structure. On the right panel of d, the molecular surface of the external cavity, viewed from the extracellular space and colour-coded by electrostatic potential ranging from blue (most positive) to red (most negative), is shown with EL3 removed for clarity.