Relationship between type I and type II estrogen binding sites in the rat uterus.

Binding parameters of type I and type II sites for (3H)-estradiol were studied in cytosol of the rat uterus using the Scatchard method and a computer program based on the analysis of Rodbard et al. The data showed that type II sites present low binding capacity, in addition to low affinity, in contrast to the previously reported high capacity for this binding molecule. These results suggest that type II sites may not be crucial in the action of estradiol at the uterine level.