FIG. 4. Activation and binding of Octopus ER at EREs. A, The OctopusERDBDactivates
transcription from a canonical ERE. Receptor
DBDs were expressed in CHO-K1 cells as a fusion protein with the
constitutively active nuclear factor-B activation domain along with
an ERE-driven luciferase reporter. Fold activation indicates luciferase
activity relative to the vector-only control, which contains no
DBD. MeanSE of three replicates is shown. B, The Octopus ER DBD
specifically binds EREs. The full-length Octopus receptor were expressed
in CHO-K1 cells, and cell extracts were tested for binding to
biotinylated ERE (all lanes). Unlabeled ERE, GRE, or ERRE were
used as competitor DNA at a 132-fold molar ratio to the labeled ERE.
Negative controls: the first lane shows a biotinylated ERE with no cell
extract added, and the second lane shows biotinylated ERE with
extract of cells transfected with the empty vector.