Fig. 8: Analysis of the TRPA1 C-terminal tail Ca²⁺/CaM binding mode.

a Overlay of the ¹⁵N-¹H HSQC spectra of ¹⁵N-labled CaM₁₂ (black) with the ¹⁵N-labeled CaM₁₂:TRPA1^1089–1119 complex (red) at a 1:1 molar ratio. Insets depict expanded view of the CSPs boxed in blue. b Overlay of the ¹⁵N-¹H HSQC spectra of ¹⁵N-labled CaM_WT (black) with the ¹⁵N-labeled CaM_WT:TRPA1^1089–1119 complex (purple) at a 1:1 molar ratio. Insets depict expanded view of the CSPs boxed in blue. a, b Higher resolution spectra are provided in Supplementary Fig. 16 and 17. c CaM₁₂ (red) and CaM_WT (black) chemical shift perturbations (CSPs) (δ_bound − δ_free) as a function of residue number for the ¹⁵N-labeled CaM₁₂:TRPA1^1089–1119 or ¹⁵N-labeled CaM_WT:TRPA1^1089–1119 complex as in (a, b), respectively. Dark and light green shadings denote CaM N- and C-lobe residues, respectively. The mean value plus one standard deviation is the horizontal blue line. d Ribbon diagram of the homology model from Fig. 7b showing only the TRPA1 distal C-terminus (yellow, residues 1100–1114) bound to the Ca²⁺/CaM C-lobe (green, residues 80–149). CaM residues exhibiting CSPs from the ¹⁵N-labeled CaM_WT:TRPA1^1089–1119 complex (black), the ¹⁵N-labeled CaM₁₂:TRPA1^1089–1119 complex (teal), and both complexes (green) that face the TRPA1 C-terminus are depicted as balls and sticks. TRPA1 DCTCaMBE residues (yellow) are depicted as balls and sticks. Dashed lines denote putative H-bond interactions. e CaM_WT (black) or CaM₁₂ (red) CSPs for the C-lobe residues modeled in (d) from the ¹⁵N-labeled CaM₁₂:TRPA1^1089–1119 or CaM_WT:TRPA1^1089–1119 complexes from (a, b), respectively.