FIGURE 3.

Domains of DmSNAP190 required for sequence-specific DNA binding by DmSNAPc. A, DmSNAP complexes FLAG affinity purified under low-salt conditions (Fig. 2C) were used for DNA mobility shift analysis with a DNA probe containing a U1 PSEA sequence. Complexes containing DmSNAP190 constructs tagged at the C terminus (N-terminal truncations) are shown in lanes 1–8, and constructs tagged at the N terminus (C-terminal truncations) are shown in lanes 9–16. Lanes 1–6 were carried out with complexes containing a normalized amount of DmSNAP190 as determined in Fig. 2C, whereas lanes 7 and 8 contained 2 or 3 times the normalized amount of truncated protein. (The maximum excess of protein that could be added was limited by the final volume of the reaction and the relative concentrations of each sample.) Lanes 9–11 also contained normalized amounts of protein, whereas lane 12 contained 3 times this amount of protein. Lanes 13–16 show a longer exposure of the same gel shown in lanes 9–12. B, similar to A except DmSNAP complexes were affinity purified under high-salt conditions and protein amounts were normalized based upon the immunoblots shown in Fig. 2D.