Figure 3.

Mass spectrometric detection of biotin accessibility of Ycg1 and Brn1. (A) Identically labeled (dark green) or unlabeled (light green) Brn1 lysines in Ycs4-BY and Ycs4-BY-DNA complexes. (B) Differentially labeled lysines of Brn1 in Ycs4-BY and Ycs4-BY-DNA complexes, including those protected by DNA binding (ruby red) and those whose accessibility was indirectly altered by DNA binding (salmon red, orange, and pink). (C) Mapping of the identically labeled and protected lysines of Ycg1 and Brn1 on the crystal structure of the Ycg1-Brn1-DNA complex. Ycg1 and Brn1 are shown in cyan and wheat colors, respectively. Blue color indicates lysine residues previously implicated in the DNA interaction.2 The three patches of modified lysines described in the text are encircled.