Extended Data Fig. 9: Binding of A-96 to TRPA1 and 2-step model of electrophile action.

a, The overall architecture of agonist-free and antagonist-bound TRPA1 is similar, representing a closed state. b, A-96 binds at the elbow of S5, sandwiched between S6 and P1. c, Binding of A-96 results in a slight shift in S5 and repositioning of F877. d, The antagonist is in an ideal position to block the straightening of the S5 elbow and inhibit channel gating. e, Two-step model of electrophile action on TRPA1. Attachment of a small electrophile to C621 results in A-loop rearrangement to the up position, bringing C665 into the reactive pocket. Modification of C665 by a second small electrophile stabilizes the A-loop in the up conformation and positions K671 at the C terminus of the TRP helix, enhancing the electric dipole of this region. f, Attachment of a large electrophile to C621 is sufficient to stabilize the A-loop in the up conformation and activate the channel. g, Increased positive electrostatic potential and charge repulsion at N termini of adjacent TRP helices initiates conformational changes associated with dilation of the lower gate. These movements are coupled to widening of the upper gate and selectivity filter through straightening of the S5 helix. The antagonist A-96 binds to the bent elbow region of S5, inhibiting straightening of the α-helix required for channel gating.