Prohibitin 2 (PHB2)

The deduced 299-amino acid protein contains 4 potential phosphorylation sites, a nuclear receptor interaction box, and a nuclear localization motif. REA suppressed activation of a reporter gene in a dose-dependent manner. REA had no effect on reporter activity in the absence of liganded ER, and it had no effect on the transcriptional activities of other hormone receptors. Mutation analysis showed that an N-terminal domain and a central domain of REA were required for its repressor activity. REA interacted directly with ER-alpha in an in vitro pull-down assay. REA did not interfere with the ability of ER-alpha to bind to estrogen response element DNA, but it competed with the coactivator SRC1 (NCOA1) for modulation of ER-alpha transcriptional activity.