SLC-ABPP CR calculation.

Cysteine-site-specific engagement was assessed by the blockage of DBIA probe labeling. Peptides showing >95% reduction in TMT intensities in electrophile-treated samples were assigned a maximum ratio of 20 for graphing purposes with preserved ranking. Peptides containing multiple cysteines with highly confident localization scores (AScore >50) were designated as separate entries. TMT reporter ion sum-signal-to-noise for each SLC-ABPP experiment was used to calculate CRs by dividing the control channel (DMSO) by the electrophile-treated channel. Replicate measurements were averaged and reported as a single entry. To avoid false positives, sites with large coefficients of variation had the highest replicate CR values removed before averaging, as previously described¹⁸.