Fig. 3. Interaction of the PDF2 gene product with the L1 box in vitro. Gel retardation assays were performed using a labeled 21-bp L1 box probe (L1) derived from the PDF1 promoter, together with the MBP alone or the PDF2 fusion protein (MBP-PDF2) as indicated. The wedge indicates increasing amounts of 100-, 300- and 1000-fold molar excesses of unlabeled L1 probe DNA in competition assays. An assay using a mutated probe (mL1) with MBP-PDF2 is also shown.