Polymorphic Alu elements have a continuum of effects on luciferase expression in an ectopic enhancer assay. (A) A genomic locus (black box) with or without the polymorphic Alu element (red) present was cloned upstream of a minimal promoter (triangle) in firefly luciferase (green) expression vector that had been modified to use Gateway cloning. (B) Luciferase measurements shown as the fold change for each locus when the Alu is present compared to when it is absent. Polymorphic Alu loci highlighted in subsequent figures (figure number in parentheses) are shown in red with chromosomal location indicated. (C) Effect of Alu orientation was evaluated by sorting results based on the orientation of the Alu with respect to luciferase in each evaluated construct. Alu orientation does not drive luciferase expression (t-test).
