Induced Effects of Sodium Ions on Dopaminergic G-Protein Coupled Receptors
Figure 1
Sodium ion's pathway into the D2 receptor, receptor stability, and conformational change of the toggle switch Trp 6.48.
(A) Volumetric map of sodium ions (yellow isosurface) within the D2 receptor at chemical potential μ = −4kBT relative to the bulk concentration of 150 mM NaCl showing the sodium ions binding sites. The ions move from the extracellular loop (EL) along negatively charged residues (orange spheres) towards the receptor interior (sites a to c) as computed from the ion concentration over 4.7 µs (MD2) of data. The volumetric map of water (blue isosurface) computed at μ = −0.5kBT relative to bulk water illustrates that part of the receptor interior is filled with water molecules including sites a, b and c. (B) The RMSD of the D2 receptor model embedded in a hydrated lipid bilayer over MD1; grey line: TM region, blue line: whole receptor including TM and loop region. (C) Depiction of the sodium ion's reaction coordinate z (blue line) and the Trp6.48 torsion angle χ2, (grey line) over MD1. Sodium transition from Asp3.32 (site a) to Asp2.50 (site c) induces a conformational change of the Trp6.48 rotamer switch.
