FIG. 3.

Comparison of EMSA patterns obtained by using oligonucleotides carrying the XMAS and X-box motifs. (A) Competition of nuclear factor binding to oligonucleotides X-HIV, mimicking the LTR region and spanning from +8 to +31, and X-DRA, carrying the X-box motif of the HLA-DRA gene, by increasing amounts of poly(dI-dC) · poly(dI-dC). Asterisk, protein-DNA complex generated by both X-HIV and X-DRA oligonucleotides. (B) Screening for the presence of XMAS and X-box motif-binding activity in different cell lines expressing or not MHC class II molecules (upper and middle panels), performed by EMSA. In the lower panel, the EMSA-grade quality of the nuclear extracts used with the X-HIV and X-DRA probes has been tested by detecting the binding of NF-κB factor to its target DNA sequence. Lane —, free probe.