An androgen binding protein in the cyst fluid of patients with polycystic ovary syndrome.

Androgen binding proteins (ABP) have not been described in the ovary. We have studied cyst fluids from three patients with the Polycystic Ovary Syndrome and one patient with choriocarcinoma for the presence of ABP. All contained a high affinity, low capacity binding protein for dihydrotestosterone and 17beta-estradiol. Comparison of this protein with the plasma androgen binding protein (TeBG) in polyacrylamide gel electrophoresis and equilibrium dialysis did not reveal any significant differences in molecular size (Kg) net charge (Yo), radius R, molecular weight (mol wt), heat stability, steroid specificity, or binding affinity (Ka). Cyst fluid and plasma could not be distinguished from each other on the basis of protein composition as measured by cellulose acetate electrophoresis. In the one patient studied, the binding capacity for DHT in cyst fluid and plasma was 58.1 and 16.1 ng/Gm protein, respectively.