FIGURE 9.

NMR spectra and structure of rat Ca²⁺/NCS-1ΔCT (PDB code 4YRU). A,¹H-¹⁵N heteronuclear single quantum coherence spectra of ¹⁵N Ca²⁺/NCS-1ΔCT; B, in the presence of 5-fold excess of D2R peptide in 50 mm Tris-HCl buffer, 50 mm NaCl, 5 mm CaCl₂, pH 6.5, 298 K. C, structure of the dimer of NCS-1ΔCT. Left, one monomer is shown as a backbone schematic and the other as a surface representation. Right, view of the hydrophobic binding site. Residues from helix 3 and the EF1/EF2 loop (Phe-48–Phe-58) are colored red, and residues in the EF3/EF4 loop region (Val-136–Pro-139) are colored brown. Conserved hydrophobic surface-exposed residues in the N-lobe site, which are involved with binding the D2R peptide, are highlighted in yellow (similar to those highlighted in Fig. 4B). D2R peptide in the N-site is shown with magenta ribbon for comparison. Ca²⁺ ions are shown as brown spheres.