Fig. 6: The TRPA1 distal C-terminus contains a high affinity Ca²⁺/CaM binding site.

Superdex 75 chromatograms of WT CaM (a) or CaM₁₂ (b) with hTRPA1^1089–1119 in the presence of 2 mM Ca²⁺ (green) or 5 mM EGTA (black). Inset 1 are zoom ins on the CaM and CaM:peptide peaks (peaks labeled 1 and 2). Inset 2 are Coomassie stains of fractions labeled 1 (green trace), 2 (black trace), and 3 (black trace). Arrows indicate CaM constructs and hTRPA1^1089–1119 peptide. c Superdex 75 chromatograms of CaM C-lobe alone (black) or with hTRPA1^1089–1119 in the presence of 2 mM Ca²⁺ (green). Chromatograms in a–c were generated from 100 µM protein for each construct. Data are representative of three independent replicates. d, e The TRPA1 distal C-terminus has a higher affinity for CaM₁₂ than WT CaM. Representative isothermal titration calorimetry plots of CaM₁₂ (d) or WT CaM (e) titrated by hTRPA1^1089–1119 peptide at 2 mM Ca²⁺ and fitted using the one-site binding model. Values for the number of binding sites (N) and the binding constant K_d are shown.