FIG. 3.

Electrophoretic mobility shift assay of Lrp binding to the wild type and to the Rm2 invertible element. The radiolabeled PCR products, encompassing all four known or potential Lrp binding sites (with flanking sequences extending to 17 bp beyond potential binding site 4 and 77 bp beyond binding site 1), were incubated with the specified amounts of purified Lrp and 5 mM and 25 mM leucine where indicated. Samples were separated into free (F) and bound species by polyacrylamide gel electrophoresis.