Fig. 5: Structural basis of GTR1 state transitions.

a Structural comparisons of the N- and C-domains of the inward- and outward-facing GTR1 structures. b Superposition of outward- and inward-facing states using the C-domains as a reference. The black arrows indicate the oscillations of the C-domains. The black box indicates the ICD. c Conformational shifts in TM7 and the ICD between the outward- and inward-facing states. Red arrows indicate the conformational shift of TM7 and the lateral helix. d–f Interaction network in the intracellular gate of the outward-facing state. The green (d, e) and orange (f) dashed lines outline the areas of interest in the outward-facing state panels. The black dashed lines indicate hydrogen bonding or electrostatic interactions. g GTL uptake by GTR1^WT and its mutants with altered intracellular interaction networks. Cells expressing GFP served as controls. Data were normalized to the total cell number for each variant and are presented relative to GTR1^WT. The values are presented as the mean ± SEM of n = 4 independent replicates.