Fig. 1.

¹H-¹³C HMQC spectra illustrating PCSs induced by lanthanide tags on methyl cross-peaks of the SNARE complex. a–d ¹H-¹³C HMQC spectra of SNARE complexes containing ²H,¹³CH₃-labeled syntaxin-1 (a, b) or synaptobrevin (c, d) SNARE motif that were untagged (black contours) or tagged at residue 166 or 41 of SNAP-25 with Dy³⁺-loaded C2 or Yb³-loaded C2 as indicated with the color codes. Regions of the spectra that were plotted at lower contour levels to allow visualization of weak cross-peaks are indicated by dashed boxes. The PCSs caused on selected cross-peaks are illustrated by dashed lines and the corresponding cross-peak assignments are indicated. Parentheses indicate tentative assignments