Fig. 4From: ECOD: identification of distant homology among multidomain and transmembrane domain proteinsHomology between MatE transporter and ABC2 transmembrane domains. Transporters are depicted in cartoon, with the cytoplasm on the bottom and transmembrane region marked by grey boxes. a MatE-like MDR efflux pump (PDB: 3mku) exhibits an internal duplication of two transmembrane bundles (TMs 1–6 and TMs 7–12), with each colored in rainbow from blue to red. A bound monovalent cation (magenta sphere) highlights an outward-facing binding site for molecules of the electrochemical gradient. b The MOP superfamily member MurJ flippase (PDB: 5 t77) adopts a similar overall duplicated topology with a C-terminal two TMH extension to the C-lobe and an inward-facing topology. A sequence motif (magenta) marks a broken TM2 that might contribute to transport. c The ABC2 transmembrane domains from the ABCG5/8 heterodimer (PDB: 5do7) retains a similar overall core topology, except with swapped N-terminal helices. The functional coupling helix (magenta) follows TM2Back to article page