Differences in the avidity of YY1 association examined for six potential binding motifs in muPARP-1.

Oligonucleotides containing the YY1 binding motif (BM1 to 5, 7) and a control (BM6) served as probes for EMSA. For each radioactive probe the binding reaction was performed either in the absence or presence of NIH3T3 nuclear extract. A third competition reactions contained a 200-fold molar excess of particular unlabeled oligonucleotides (BM 1–7) in order to illustrate the specificity of the protein:DNA interactions. A fourth reaction contained anti-YY1 antibody (H-414; Santa Cruz). Samples were run on an 8% polyacrylamide gel. Arrows indicate bands shifted by YY1/oligonucleotide binding alone (central lines in each group) whereas supershifts by the antibody are evident in the rightmost lanes for BM1, BM4 and BM7. Inset – Immunoblot analysis of NIH3T3 cell lysates revealed the presence of a degradation product (YY1*), as already reported [52].