Fig. 3.

The affinity of PCNA-PIP box interactions is reduced by PCNA^S228I variant. Affinity curves generated from SPR data for His-S-PCNA^WT or His-S-PCNA^S228I binding to CM5 chip coupled to indicated GST-PIP peptide. PCNA^WT is shown in black, PCNA^S228I in grey. GST-mutated p21 PIP peptide (GST-p21*) is also shown on the p21 graph (A) with triangle marker points; no binding of either PCNA^WT or PCNA^S228I to GST-p21* peptide lane was observed. K_D calculated from Biacore T200 evaluation software indicated on relevant curves. ND = not determined.