Figure 4.
Conformational changes experienced by the C-terminal α-13 helix upon glucose binding. (A) The α-13 helix (red) is solvent exposed and released from the connecting loop (yellow) in the unliganded state. (B) In the presence of glucose and an allosteric activator (not shown), the α-13 helix is constrained by the connecting loop. Experiments indicate that fusion of additional residues at the C-terminus has no effect upon steady-state kinetic properties, an observation that is difficult to reconcile with this structural data. Image was generated using PDB entry 1V4T, 1V4S [85] and PyMol 1.1 [108].