Alphafetoprotein is not a component of the 8 S estradiol receptor from the immature mouse uterus or brain

The hypothesis that alphafetoprotein (AFP) could be a consitituent of the estradiol receptor in the uterus and brain of the immature mouse has been tested. Cytosols prepared from 2 week-old mice were depleted of AFP by immunoadsorption with a Sepharose-coupled anti-mouse AFP anti-serum. Aliquots of these cytosols containing nondetectable levels of AFP by RIA were then brought to 0.4 M KCl to convert 8 S estradiol receptors to the 4-5 S forms, reacted either with anti-AFP or with a control anti-IgG immunoadsorbent, labeled with 3H-estradiol, and centrifuged on glycerol gradients. There was no, or very little, loss of estradiol receptors in the experimental as compared to the control cytosols indicating that AFP is not a constituent of the 8 S estradiol receptor.