Fig. 3: Structure of the pore domain of NALCN.
From: Structure of voltage-modulated sodium-selective NALCN-FAM155A channel complex
a A cut-open side view of NACLN and FAM155A complex. The surface electrostatic potential is calculated by APBS51. The ion permeation pathway is shown as a yellow line. b Pore profile of NALCN channel shows two constrictions. c The ion permeation pathway of the pore domain, calculated with HOLE52, is shown as color dots. Purple, green, and red dots represent pore radii >2.8 Å, 1.4–2.8 Å, and <1.4 Å, respectively. d Sequence alignment of the residues around the selectivity filter of rat NALCN. Residues that participate in ion permeation are highlighted in yellow. Residues for predicted selectivity filter are indicated with an arrow. e Densities of the selectivity filter of each repeat, shown as gray mesh, are contoured at 3.5 σ. f Side view of the structural comparison of domain IV between CaV1.1 (gray) and NALCN (blue). Key residues are shown as sticks. The yellow box indicates the approximate position of the high field strength layer of the selectivity filter. g Structural comparisons of the selectivity filter of NALCN, NaV1.4 (PDB: 6AGF), and CaV1.1 (PDB: 5GJV). Key residues are shown as sticks. h, Relative ion permeability ratios (PNa/PX) of NALCN and its mutants. Data are presented as mean ± s.d., n = 3 biologically independent cells. Two-tailed unpaired Student’s t-test was applied, and P-values were indicated in the figure. P < 0.05 was considered statistically significant. NS no significance. Source data are provided as a Source Data file. i Structure of S6 segments. π-bulges are highlighted in red. j Top view of the intracellular gate, hydrophobic residues forming the narrowest constrictions are shown as sticks. k Side view of the intracellular exit for sodium. The gray surface represents the calculated ion permeation pathway.
