title: Estradiol binding activity in epididymal cytosol of the turtle, Chrysemys picta.
abstract: Estrogen binding activity was investigated in the epididymis of the turtle, Chrysemys picta using DNA-cellulose affinity chromatography. A component binding estradiol-17 beta specifically with high affinity (Kd:8.0 X 10(-10) M) and limited capacity (20 fmol/mg protein) was demonstrated in the epididymal cytosol. In addition, binding of estradiol-17 beta was sensitive to excess (100-fold) diethylstilbestrol or natural estrogens (estradiol-17 beta, estrone, and estriol) but not to progesterone or androgens (testosterone and 5 alpha-dihydrotestosterone). The specific estrogen binding macromolecules eluted from DNA-cellulose columns sedimented at 4-5 S in linear 5-20% sucrose gradients. These characteristics suggest the presence of an estrogen receptor in this androgen target organ.
mesh_terms: D000818:Animals; D001667:Binding, Competitive; D002846:Chromatography, Affinity; D003600:Cytosol / Q000378:metabolism; D004822:Epididymis / Q000378:metabolism*; D004958:Estradiol / Q000378:metabolism*; D008297:Male; D014426:Turtles / Q000378:metabolism*
chemical_list: D004958:Estradiol