Autoradiograph showing products of a strand displacement assay. 6 nM substrate was incubated in the presence of various concentrations of protein (nM dodecamer, as indicated) for 30 min at 50°C. Lane 1, labelled oligonucleotide used in substrate extension reaction; lane 2, DNA ladder; lane 3, reaction incubated on ice; lane 4, boiled substrate; lane 5, reaction without protein; lanes 6-8, increasing concentrations of WT protein; lanes 9-11, increasing concentrations of RRAA protein; lanes 12-14, increasing concentrations of R137A protein.