FIGURE 3.

Dpb11 activation of Mec1 is largely independent of DNA. A, Rad53-kd phosphorylation by Mec1 (5 nm) was determined at the indicated NaCl levels in the absence of Dpb11 (1st panel), with 5 nm Dpb11 (2nd panel), or with 5 nm Dpb11 and 15 μm (nucleotide) deca-primed single-stranded Bluescript DNA (3rd panel). B, Rad53-kd phosphorylation from A was quantified and plotted as a function of mm NaCl. C, Rad53-kd phosphorylation by Mec1 (5 nm) was determined at 80 mm NaCl in the absence of Dpb11 (1st panel), or with 5 nm Dpb11 (2nd panel), or with 5 nm Dpb11 and 150 nm RPA (3rd panel). Double-stranded or deca-primed single-stranded Bluescript DNA, with or without prior UV (1500 J/m²) treatment, was added as indicated. The phosphorylation signal ratios (2nd panel/1st panel) and (3rd panel/2nd panel) are shown.