Insulin binding to human ovaries

Human ovarian tissue samples were obtained at the time of laparotomy, and plasma membrane fractions were prepared and used in receptor assays. Incubations of the membrane fraction were performed with [125I]insulin (porcine), and Scatchard analysis of binding showed biphasic curves. The high affinity sites had an average concentration of 57.4 +/- 7.9 (+/- SEM) fmol/mg protein and a dissociation constant of 3.5 +/- 0.9 nM (n = 9). Neither affinity nor number of binding sites changed significantly during the menstrual cycle. We conclude that there is high affinity binding of [125I]insulin to human ovarian plasma membranes.