Figure 2.

Tris, but not glycine, quenching reverses ChIP signal over time. A, average TBP ChIP signal at the URA1 locus in cells cross-linked with 1% formaldehyde, quenched with 250 mm glycine, and resuspended in either 50 or 750 mm Tris, pH 8. Samples were incubated at room temperature for 10 (blue circles) or 30 (red circles) min before processing. A Student's t test was performed to determine statistical significance between conditions. B, average ChIP signal of cells cross-linked with 5% formaldehyde and quenched with 2.93 m glycine, pH 5. Samples were incubated in glycine-quench solution for 0, 10, or 30 min before processing. All experiments were performed with two biological replicate samples, and error bars represent the standard deviation. *, p < 0.05.