Figure 8.

Active-site geometry explains Gat1's preference for UDP-Gal rather than UDP-Glc. Comparison of the sugar-binding pockets of PuGat1 and Oc-glycogenin-1 displayed as wall-eyed stereo view. A, the Glc moiety is modeled based on the Oc-glycogenin-1 crystal structure with its intact sugar nucleotide. B, the Gal moiety is modeled by flipping the stereochemistry of Glc at the C4′ position. PuGat1 and glycogenin-1 side chains are represented by green and gray sticks, respectively, the yellow dashes represent hydrogen bonds, and water molecules are represented by blue spheres.