Immunorecognition of cytosol and nuclear estradiol receptor of fetal guinea pig uterus using monoclonal antibody.

Using a monoclonal antibody to estrogen receptor obtained from a preparation of extranuclear receptor of MCF-7 human breast cancer, it is observed that this antibody recognizes the estrogen receptor in both the cytosol and nuclear fractions of the fetal guinea pig uterus. In sucrose gradient ultracentrifugation (10-30% w/v, 0.4 M KCl), the cytosol estrogen receptor complex, which migrates with a coefficient of sedimentation of 4.5 S, is shifted to 7.4 S when bound to the estrogen receptor monoclonal antibody. For the nuclear fraction, the respective values are 5 S and 7.8 S.