Fig. 7: Schematic of the gating mechanism of GLIC. | Nature Communications

Fig. 7: Schematic of the gating mechanism of GLIC.

From: Cryo-EM structures of prokaryotic ligand-gated ion channel GLIC provide insights into gating in a lipid environment

Fig. 7

The activation pathway of GLIC is shown with a resting state represented by our structures at pH 7.5, two putative intermediate states observed at pH 5.5 and pH 4.0 (C1), a putative pre-open state with a wider pore at I9ʹ and outward movement of M2–M3 loop (C2), and an open state represented by the O structure at pH 4.0 with a maximally open pore. Lipid 2 is observed in all the structures. An acyl chain of Lipid 2 wedging into a cavity is observed only in C2 and O states. Lipid 9 is observed in both putative pre-open (C2) and open states. In the open state, the pore is wider than all other structures, along with a counter-clockwise rotation of the upper part of the M2 helix and outward motion of the M2–M3 loop. All protonated structures show counter-clockwise rotation and compaction of the ECD compared to the resting state. The representative closed (PDB: 4NPQ) and putative open (PDB: 4HFI) structures solved by crystallography are placed on the activation pathway along with all the structures in the current study. A desensitized state (?) is not observed in our study. A key for various elements used for depiction is given at the bottom.

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