Binding characteristics of [3H]delta(5)-androstene-3beta,17beta-diol to a nuclear protein in the rabbit vagina.
In this study, we investigated the binding characteristics of [3H]Delta(5)-androstene-3beta,17beta-diol to rabbit vaginal cytosolic and nuclear extracts and in freshly excised intact tissue strips. [3H]delta(5)-Androstene-3beta,17beta-diol bound to a protein(s) in the vaginal nuclear extract with high affinity (K(d)=3-5 nM) and limited capacity (50-100 fmol/mg protein). No specific binding was detected in the cytoplasmic extracts. Competitive binding studies showed that binding of [3H]delta(5)-androstene-3beta,17beta-diol was effectively displaced with unlabeled delta(5)-androstene-3beta,17beta-diol but not with dehydroepiandrosterone, testosterone, dihydrotestosterone, triamcinolone acetonide, or progesterone. However, estradiol at high concentrations partially displaced bound [3H]delta(5)-androstene-3beta,17beta-diol. Incubation of freshly excised vaginal tissue strips with [3H]delta(5)-androstene-3beta,17beta-diol in the absence or presence of excess unlabeled delta(5)-androstene-3beta,17beta-diol for 1h at 37 degrees C resulted in specific binding to a soluble macromolecule in the nuclear KCl extracts. In addition, quantitative measurement of estrogen receptor, androgen receptor and delta(5)-androstene-3beta,17beta-diol binding protein was performed by equilibrium ligand binding assays using extracts of distal vaginal tissue from intact animals or ovariectomized animals treated for 2 weeks with vehicle, estradiol, testosterone, or estradiol plus testosterone. These changes in steroid hormone levels resulted in opposing trends between the estrogen receptor and delta(5)-androstene-3beta,17beta-diol binding protein, suggesting that delta(5)-androstene-3beta,17beta-diol binding protein is regulated differently by the hormonal milieu than the estrogen receptor. These data suggest that rabbit vaginal tissue expresses a novel binding protein which specifically binds delta(5)-androstene-3beta,17beta-diol and is distinct from the androgen and estrogen receptors.
Traish
Abdulmaged M
AM
Department of Biochemistry, Boston University School of Medicine, 700 Albany Street, Room W607, Boston, MA 02118, USA. atraish@bu.edu
Huang
Yue Hua
YH
Min
Kweonsik
K
Kim
Noel N
NN
Munarriz
Ricardo
R
Goldstein
Irwin
I
D015113:Androstane-3,17-diol / Q000378:metabolism*; D000737:Androstenols / Q000378:metabolism*; D000818:Animals; D001667:Binding, Competitive; D003600:Cytosol / Q000737:chemistry / Q000378:metabolism; D005260:Female; D009687:Nuclear Proteins / Q000737:chemistry / Q000378:metabolism*; D010052:Ovariectomy; D011485:Protein Binding; D011817:Rabbits; D011944:Receptors, Androgen / Q000378:metabolism; D011960:Receptors, Estrogen / Q000378:metabolism; D014621:Vagina / Q000737:chemistry / Q000378:metabolism*
D000737:Androstenols; D009687:Nuclear Proteins; D011944:Receptors, Androgen; D011960:Receptors, Estrogen; D015113:Androstane-3,17-diol