FIG 6.

Nucleic acid-binding activity of the Plus3 domain is mutually exclusive with pSpt5 binding. (A to C) EMSAs using an FITC-labeled ssDNA probe and 1× to 5× molar equivalents of the indicated Prf1 Plus3 domain. The lane marked “Plus3” contains the wild-type Plus3 domain at a 1× concentration. (D) Competition experiments using an ssDNA probe, a 1× molar equivalent of the Prf1 Plus3 domain, and the Spt5 CTD peptide (either phosphorylated or unphosphorylated) added at 1× to 5× molar ratios to the probe. (E and F) Competition experiments using an ssDNA probe, a 1× molar equivalent of the Prf1 Plus3 domain, and the Rpb1 CTD peptide (either unphosphorylated or phosphorylated at serines 5 and 2) added at 1× to 5× molar ratios to the probe. For all experiments, the predominant shifted band is denoted with an arrow. * indicates the free probe. All experiments were repeated at least 3 independent times, and representative images are shown.