Fx. Claret et al., 2 FUNCTIONAL FORMS OF THE XENOPUS-LAEVIS ESTROGEN-RECEPTOR TRANSLATEDFROM A SINGLE MESSENGER-RNA SPECIES, The Journal of biological chemistry, 269(19), 1994, pp. 14047-14055
Steroid receptors are nuclear proteins that regulate gene transcriptio
n in a ligand-dependent manner. Overexpression of the Xenopus estrogen
receptor in a vaccinia virus derived expression system revealed that
the receptor localized exclusively in the nucleus of the infected cell
s, irrespective of the presence or absence of the ligand. Furthermore,
two forms of the receptor were produced, a full-length and a N-termin
al truncated version, which are translated from a single mRNA species
by the use of two AUG within the same reading frame. These 66- and 61-
kDa receptors were also observed after in vitro translation of the mRN
A as well as in primary Xenopus hepatocytes. Both forms are potent est
rogen dependent transcriptional activators in transient transfection e
xperiments, as well as in in vitro transcription assays.