Potential assignments for peptides obtained by tryptic digestion of cross-linked complex between PTP-SL and ERK2.

Sequence data corresponding to peptides formed by intramolecular cross-linking of PTP-SL are written in italics. Lysine residues potentially involved in cross-linking through BS3 are underlined (numbering is mentioned as superscript). “Wox ”denotes the oxidized form of tryptophan. “1” and “2” between parantheses refer to the number of predicted missed cleavage sites.