<p><i>egl-2</i> encodes the sole <i>C. elegans</i> EAG potassium channel.</p>

(<b>B</b>) Amino acid sequence alignment of a conserved region within the CNBHD of EAG1 orthologs from the indicated species. The glycine residue corresponding to G574 in EGL-2 (highlighted in yellow) is highly conserved and resides within the first α-helix of the CNBHD. Asterisks indicate identical residues; colons indicate conserved residues.

(<b>C-F</b>) Structural models of EGL-2/EAG predicted by AlphaFold3, shown in cartoon representations, with the residue G574 highlighted in red. (C) Side view of a single subunit; (D) Side view of the tetrameric EGL-2 channel; (E) Bottom view of the tetrameric channel showing only the PAS domains and CNBHDs for better visualization of the location of the residue G574; (F) Magnified view of the region between two adjacent CNBHDs, as boxed in (E).

Domains are colored as indicated in the diagram at the bottom, with residue numbering based on EGL-2 isoform a. The red star indicates the glycine (G574) mutated in <i>egl-2(sy985)</i> and <i>egl-2(tan200)</i>. (<b>G-H</b>) Sphere representations of the AlphaFold3-predicted structure of the homotetrameric EGL-2 channel, showing the inter-subunit arrangement of the PAS domains and CNBHDs within the intracellular ring.

The four subunits are colored yellow, green, orange, and purple. Other domains are omitted for better visualization of G574 (in red) at the CNBHD-CNBHD interface<b>. (G)</b> Bottom view of the intracellular gating ring of EGL-2 channel.

The CNBHDs form the inner ring, with the PAS domains positioned peripherally. <b>(H)</b> Side view of two CNBHDs from adjacent subunits, highlighting the position of G574 (in red) at the interface, generated by a 90° downward rotation of the bottom views shown in (G) and displayed at higher magnification, with the PAS domains omitted for clarity. Top, opaque sphere representation of two adjacent CNBHDs; bottom, magnified view of a smaller region containing the CNBHD-CNBHD interface at 70% transparency.</p>