FIG. 3.

Deletion of the LR does not eliminate interaction of ORF50/Rta with RBP-Jk or promoter DNA. (A) GST-RBP-Jk or the GST moiety alone was purified and tested for binding to RRLs programmed with plasmids expressing the indicated proteins. The proteins were labeled cotranslationally by addition of L-[³⁵S]-methionine to the RRLs. Bound proteins were visualized by autoradiography after being displayed by SDS-PAGE. Five percent of the input protein was also analyzed as a size reference. (B) WT ORF50 (50WT) or ORF50ΔLR (50ΔLR) was expressed and purified as a fusion to the MBP and tested in increasing amounts for binding to ³²P-labeled oligos of the Rta binding sites from the indicated promoters. 0, lanes containing labeled DNA mixed with buffer in the absence of protein.