Slipknotted and unknotted monovalent cation-proton antiporters evolved from a common ancestor
Fig 2
Conserved helical region (core) found in the monovalent cation-proton antiporter superfamily.
Conservation of this region suggests that three different fold types, including one possessing a non-trivial topology (a slipknot), evolved from a common, single-domain ancestor. The putative ancestor is shown in light green box in the middle. Three arrows from the ancestor navigate to three proteins with different folds: 1) left—two-domain slipknotted protein; 2) middle—one-domain unknotted protein; 3) right—two-domain unknotted protein. On the bottom left of the figure is shown a schematic diagram of the entangled region of the slipknotted protein colored from blue (N-terminal) to red (C-terminal). On the bottom right there is a similar schematic diagram that shows the topology of the unknotted protein backbone.