Figure 3. Rub binding to GLUTs.

(a) and (b) Cytosolic face of GLUT is oriented towards the top, and helices 8 and 9 have been removed for better visualization. Images were generated with MolScript³² and raster3D³³. (a) Modeled GLUT5 with docked Rub. Predicted Rub-interacting residues are: Q288 and Q289 from helix 7, N325 from helix 8, and S392 from helix 10. (b) GLUT1 (PDB ID 4PYP) with docked Rub. Predicted interacting residues are: Q282 and Q283 from helix 7, W388 from helix 10, and N411 from helix 11. (c) Comparison of space-filling models of GLUT1 (white in N-domain, light purple in C-domain) and GLUT5 (blue in N-domain, magenta in C-domain) interacting with Rub (shown as stick molecule, in yellow for GLUT1, and green for GLUT5). Molecular graphics and analyses were performed with the UCSF Chimera package³⁴. (d) Rub as it docked to GLUT5 binding site. The distance between 4-oxygen positions of the end glucosides is 13 Å. (e) Rub as it docked to GLUT1 binding site. The distance between 4-oxygen positions of the two glucosides is 18 Å. (f) Alignment of GLUT1-5, 7 residues predicted to interact with Rub. (g) Model of Ast6G, with the astragalin head modeled onto isomaltooctaose chain from PDB ID 3WNN.