Fig. 4. EMSA of UVB-irradiated oligo by PARP. (A) Dose dependent binding of PARP to UVB-irradiated oligo. The unirradiated and UVB-irradiated 50 bp oligo were reacted with 0-36 ng of PARP and resolved on neutral 1.5% agarose-TBE gel. Gels were dried and analysed using an instant imager (top panel). The cpm in each band of oligo-PARP complex from four independent experiments were pooled and shown here as mean±s.d. (bottom panel). (B) Specificity of interaction of PARP with UVB-irradiated oligo. Purified PARP (45 ng) was reacted with 5 ng of one of the three oligos: unirradiated control (lanes 1 and 2), 3.2 kJ/m² UVB-irradiated (lanes 3 and 4) or UVB + T4 EndoV-treated (lanes 5 and 6). Samples were resolved on agarose gel and analysed, as described above. For immune competition study, anti-PARP C-2-10 (1:100) was added prior to reaction with UVB-irradiated oligo (lane 7). Data are from one of three experiments with identical results.