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 of the oviduct of Alligator mississippiensis was assayed for the presence of receptors for estrogen and progesterone. In the presence of [3H]-estradiol-17 beta, the extract contained an estrogen-binding activity which reached equilibrium at 25 degrees C in 1 h. Scatchard analysis demonstrated that a single estrogen-binding activity was present in the extract with a Kd of 0.5 nM for [3H]estradiol-17 beta. A steroid specificity competition assay showed the estrogen binding activity strongly recognized estradiol-17 beta and diethylstilbestrol (DES) and weakly interacted with estrone, estriol, estradiol-17 alpha, and dihydrotestosterone (DHT). The estrogen binding activity did not recognize testosterone, 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 progestin R5020 with a Kd of 0.9 nM. This binding activity recognized 17 alpha-estradiol, dexamethasone, testosterone, and estriol. This activity did not recognize DHT, DES, or estradiol-17 beta. These data suggest the presence of estrogen and progesterone receptors in the oviduct of the alligator.
Vonier
P M
PM
Tulane-Xavier Center for Bioenvironmental Research Environmental Endocrinology Project, Tulane University, New Orleans, Louisiana 70112, USA.
Guillette
L J
LJ
McLachlan
J A
JA
Arnold
S F
SF
D000489:Alligators and Crocodiles / Q000378:metabolism*; D000818:Animals; D001667:Binding, Competitive; D004268:DNA-Binding Proteins / Q000378:metabolism; D004958:Estradiol / Q000378:metabolism; D005260:Female; D010057:Oviducts / Q000378:metabolism*; D011959:Receptors, Estradiol / Q000737:chemistry; D011960:Receptors, Estrogen / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D011980:Receptors, Progesterone / Q000737:chemistry*
D004268:DNA-Binding Proteins; D011959:Receptors, Estradiol; D011960:Receptors, Estrogen; D011980:Receptors, Progesterone; D004958:Estradiol