Fig. 3

Substrate-binding site and movement of the HP2 loop. a, b Superposition of the inward-open ASCT2_C467R in presence of TBOA (shown in blue with the HP2 loop in purple) and the substrate-bound inward-occluded ASCT2_wt (shown in grey, PDB-ID: 6GCT), demonstrating the movement of HP2. b Non-protein density (shown as red mesh at 3σ) located near HP1 and HP2 with a modelled diundecylphosphidylcholine and putatively coordinating residues shown as sticks. The lipid head group is positioned between the HP1 and HP2 loops and its negative charge appears to be stabilised by the helix dipole of hairpin helix HP2b. a, b Structures were superimposed on the transport domain