view article
Figure 3
Arg149 is a binding residue and also a gating residue. (a) Bent Arg149 at the sugar-binding state. A bent Arg149 is illustrated from the melibiose-bound outward-facing conformation (PDB entry 9olp). Water molecules (Wat) are colored red. (b) Extended Arg149 in the sugar low-affinity inward-facing conformation (PDB entry 8t60). Na+ is shown as a blue sphere. (c) Overlay. The boxed region in (a) and (b) was enlarged as indicated. Arg149 and Trp342 from the higher affinity sugar-bound and empty low-affinity conformations are colored yellow and pink, respectively; the melibiose molecule bound to the outward-facing structure is colored cyan.

Journal logoSTRUCTURAL
BIOLOGY
ISSN: 2059-7983
Volume 82| Part 9| September 2026| Pages 1030-1043
https://doi.org/10.1107/S2059798326007485