title: alpha-Foetoprotein:immunoreactivity of the major oestrogen-binding component in mouse amniotic fluid.
abstract: Competitive protein binding studies, using oestrone as the inhibitor, demonstrated that mouse amniotic fluid contains a high affinity oestradiol-binding component precipitable by monospecific rabbit anti-alpha-foetoprotein (AFP) in a double-antibody radio-immunoassay. On disc gel radio-electrophoresis the oestrogen-binding entity migrated as an alpha-1 protein which was immunoreactive to anti-AFP serum. Immunoprecipitation of protein-bound [3H]-oestradiol from solution was proportional to anti-AFP immunoglobulin G concentration. Rabbit antisera directed against other major proteins in amniotic fluid did not produce significant precipitation of radioactivity. Only when anti-AFP antiserum was the complexing protein and AFP, either crude or purified, was the binding protein did a substantial [3H]-oestradiol precipitate form. Our data suggest that oestradiol and anti-AFP do not bind at the same sites on the AFP molecule and that estradiol does not serve as a hapten in the production of anti-AFP serum in rabbits.
mesh_terms: D000653:Amniotic Fluid / Q000276:immunology*; D000818:Animals; D001667:Binding, Competitive; D011232:Chemical Precipitation; D004591:Electrophoresis, Polyacrylamide Gel; D000939:Epitopes; D004958:Estradiol / Q000276:immunology / Q000378:metabolism; D005260:Female; D006241:Haptens; D007106:Immune Sera; D051379:Mice; D011247:Pregnancy; D011485:Protein Binding; D011863:Radioimmunoassay; D000509:alpha-Fetoproteins / Q000276:immunology*
chemical_list: D000939:Epitopes; D006241:Haptens; D007106:Immune Sera; D000509:alpha-Fetoproteins; D004958:Estradiol