Figure 3.

The grid-like noncovalently interacting mesh network along the PE-dependent minimal gating pathway of the PE-free closed state 4 of the rTRPV2 channel at pH8 and 4 °C. (A) The thermoring structure based on cryo-EM data of a single subunit of the PE-free closed rTRPV2 channel in DMNG at pH8 and 4 °C (PDB ID, 5HI9). The pore domain, the S4–S5 linker, the TRP domain, and the pre-S1 domain are indicated by black arrows, except for the VSLD. Salt bridges, π interactions, and H-bonds between paired amino acid side chains along the PE-dependent minimal gating pathway from W351 to W703 are denoted in purple, green, and orange, respectively. The specific grid sizes necessary to regulate the least-stable noncovalent interactions in the grids are indicated with black numbers. The H438-R490 cation-π interaction in the biggest Grid₁₉ is emphasized in yellow. The total grid sizes and the total grid size-controlled noncovalent interactions along the PE-dependent minimal gating pathway are displayed in cyan and black circles, respectively. (B) The structure of the biggest Grid₁₉ with a 19-residue size to regulate the H438-R490 cation-π interaction in the VSLD. (C) The structure of the putatively thermosensitive Grid₂ with a 2-residue size to regulate the H438-R490 cation-π interaction in the VSLD. (D) The sequence of the biggest Grid₁₉ to control the H438-R490 cation-π interaction highlighted in the blue box. Additionally, sequence alignment of the putatively thermosensitive Grid₂ is shown between rTRPV2 and hTRPV2.