FIGURE 2.

HEXIM1 and LaRP7 bind to M3 and M8, respectively, in cells. CAT plasmid targets were constructed by replacing TAR in HIVSCAT with the sequence of 7SK. The RNA sequence and putative secondary structure of each reporter are presented above the CAT data. A schematic of plasmid targets and effectors is shown left of the CAT data. The 7SK plasmid targets (indicated in each panel of CAT data) were coexpressed with effectors, which are shown below the CAT data, in HeLa cells. CAT data are presented as fold activation by calculating relative CAT values obtained with Tat48 fusion proteins (columns with even numbers) over the cognate non-fusion protein (columns with odd numbers) on each reporter. Error bars represent mean ± S.E. of experiments performed in triplicate. The expression of the effector proteins was determined by Western blotting with anti-cMyc antibodies and tubulin as the loading control (bottom panel). m, cMyc epitope tag. pA, polyadenylation site.