Fig. 3: Structural rearrangements upon proton binding and gating in GLIC.
From: Disentangling the mechanistic role of loop-C capping in Cys-loop receptor activation
a–d Different views of globally superposed atomic models of closed (pH 7.5; PDB ID: 8I4234) and open (pH 4.0; PDB ID: 8WCR34) GLIC. One subunit is highlighted, and its loop C (sequence: ANFALEDRLE) is colored blue (pH 7.5) or red (pH 4.0); all other atoms are colored yellow (pH 7.5) or dark cyan (pH 4.0). Different structural elements at the ECD–TMD interface are indicated. The functional role of loop-C capping in GLIC remains enigmatic inasmuch as deleting all five loops C (from full-length GLIC)—much as we did here in the context of ECD–TMD chimeras—had, essentially, no effect on proton-gated currents28. Compared to small-molecule gated Cys-loop receptors from animals, GLIC has a much shorter M3–M4 linker. The molecular images were made with VMD57 using cartoon representation.
