V. Cavailles et al., INTERACTION OF PROTEINS WITH TRANSCRIPTIONALLY ACTIVE ESTROGEN-RECEPTORS, Proceedings of the National Academy of Sciences of the United Statesof America, 91(21), 1994, pp. 10009-10013
The ligand binding domain of the estrogen receptor contains a hormone-
dependent transcriptional activation function. To investigate the mech
anism by which it stimulates transcription, we have expressed fusion p
roteins containing either the wild-type or a transcriptionally defecti
ve form of this domain fused to glutathione-S-transferase and searched
for proteins that specifically interact in vitro. By far-Western blot
ting, three proteins of 160, 140, and 80 kDa expressed in different ma
mmalian tells (HeLa, ZR75-1, and COS-1) were shown to associate direct
ly with the wild-type receptor in the presence of estrogen. Two additi
onal proteins appeared to interact indirectly with the hormone binding
domain since they were detected only by a pull-down assay. All of the
se interactions were abolished by antiestrogens, such as 4-hydroxytamo
xifen, ICI 164384, or ICI 182780, which inhibit hormone-dependent tran
scription. Moreover, they were not observed with the transcriptionally
defective form of the receptor even in the presence of estrogen. Thus
, since the ability of these proteins to interact with the hormone bin
ding domain correlates with its transcriptional activity, one or more
of them may contribute to hormone-dependent transcriptional activation
by the estrogen receptor.