Immunological difference between ribonuclease and temperature, time and salt-induced forms of the estrogen receptor detected by a monoclonal antibody

Abstract

The effect of RNAase A on the activation of the estrogen receptor from fetal guinea pig uterus was studied by DNA-cellulose binding assay and immunorecognition of the estradiol-receptor complex by the monoclonal antibody D547 raised against the human estrogen receptor. After RNAase treatment at 4°C or 25°C the binding of the receptor to DNA-cellulose doubled. This stimulation was partially prevented by sodium molybdate. RNAase treatment did not modify the interaction of the receptor with the monoclonal antibody D547; this antibody, as was demonstrated previously, selectively recognizes the activated form of the receptor when activation has been induced by temperature, time or high salt concentrations. In addition, RNAase had little or no effect on the transformation of the 8–9 S receptor to more slowly sedimenting forms under low salt concentrations. These observations suggest that even if RNAase induces receptor activation, which can be inferred from the increase in its binding to DNA-cellulose, the conformational modifications of the receptor molecule involved in this process are apparently different from those induced by factors such as temperature, time or high-salt concentrations.