IDENTIFICATION AND CHARACTERIZATION OF ESTROGEN AND PROGESTERONE RECEPTORS FROM THE OVIDUCT OF THE AMERICAN ALLIGATOR (ALLIGATOR-MISSISSIPPIENSIS)

A protein extract prepared from the egg shell fiber-secreting region o f the oviduct of Alligator mississippiensis was assayed for the presen ce of receptors for estrogen and progesterone, In the presence of [H-3 ]estradiol-17 beta, the extract contained an estrogen-binding activity which reached equilibrium at 25 degrees C is 1 h, Scatchard analysis demonstrated that a single estrogen-binding activity was present in th e extract with a Kd of 0.5 nM, for [H-3]estradiol-17 beta. A steroid s pecificity competition assay showed the estrogen binding activity stro ngly recognized estradiol-17 beta and diethylstilbestrol (DES) and wea kly interacted with estrone, estriol, estradiol-17 alpha, and dihydrot estosterone (DHT), The estrogen binding activity did not recognize tes tosterone, dexamethasone or progesterone, The extract exhibited a DNA- binding activity that recognized an estrogen response element in a gel mobility shift assay, We have also identified a high affinity binding activity in the extract that specifically recognized the synthetic pr ogestin R5020 with a Kd of 0.9 nM, This binding activity recognized 17 alpha-estradiol, dexamethasone, testosterone, and estriol, This activ ity did not recognize DHT, DES, or estradiol-17 beta. These data sugge st the presence of estrogen and progesterone receptors in the oviduct of the alligator. (C) 1997 Academic Press.