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. Author manuscript; available in PMC: 2017 Jun 4.
Published in final edited form as: Curr Opin Struct Biol. 2016 Jun 4;38:9–17. doi: 10.1016/j.sbi.2016.05.001

Figure 5.

Figure 5

Three topological types of nonhomologous PTS group translocators (IIC domains). A. the Glucose/Fructose/Lactose (GFL) Superfamily. B. the Ascorbate/Galactitol (AG) Superfamily, and C. the Mannose (Man) Superfamily. All PTS Enzyme II complexes have IIA, IIB and IIC proteins or protein domains, but Man family complexes also have a IID constituent. PTS IIC domains have apparently evolved 3 times independently of each other, giving rise to the three predicted topological types shown. Boxes, circles, ovals and rectangles indicate the four different structural folds believed to represent the three independently evolving superfamilies of PTS porters (IIC proteins and protein domains).