P. Yang et al., Human foamy virus Bel 1 transactivator/estrogen receptor fusion proteins allow inducible transactivation of both human foamy virus promoters, VIRUS GENES, 21(3), 2000, pp. 209-213
Recombinant plasmids that express human foamy virus (HFV) Bel 1 transactiva
tor and human estrogen receptor (ER) fusion proteins were constructed. The
HFV bel 1 gene was inserted up- and downstream of the ER gene. Recombinant
Bel 1-ER and ER-Bel 1 fusion proteins were expressed in eukaryotic cells. I
n the absence of estrogen, the ER moiety of the fusion proteins suppressed
Bel 1-mediated transactivation as measured in CAT reporter gene-based trans
activation assays. However, transactivation of the HFV LTR and the HFV inte
rnal promoter by Bel 1-ER and ER-Bel 1 fusion proteins was recovered in the
presence of estrogen. Thus, the transactivation function of the Bel 1 moie
ty of the chimeric Bel 1-ER fusion proteins can be efficiently, specificall
y, and intentionally activated and inactivated by simply adding the low-mol
ecular weight effector estrogen.