Binding of an inhibin-like protein from bull seminal plasma to ovine pituitary membranes

Autor: M. R. Ranganathan, K. Ramasharma, M. R. Sairam
Rok vydání: 1981
Předmět:
Zdroj: Molecular and Cellular Endocrinology. 22:251-264
ISSN: 0303-7207
DOI: 10.1016/0303-7207(81)90095-2
Popis: A purified basic protein from bull seminal plasma having inhibin activity was labeled with 125 I and tested for binding with ovine pituitary membrane fractions. The bound radioactivity could be eluted under acidic conditions and shown to rebind to fresh pituitary membranes. The properties of the eluted labeled inhibin were similar to the unlabeled fraction. The eluted labeled inhibin exhibited specific binding to the membranes, which was displaceable in a dose-dependent manner by an unlabeled active fraction. Only those fractions in the purification scheme which had inhibin activity also competed for the binding. A bovine follicular fluid fraction with molecular weight > 10 000 and inhibin activity also displaced the bound radioactivity from the membranes. Other purified hormones such as ovine FSH, LH or their subunits, prolactin or bovine serum albumin, dialyzed serum or unrelated basic macromolecules such as lysozyme, polylysine, histones, had no influence on the binding of labeled inhibin to ovine pituitary membranes. Synthetic LH-RH also failed to displace the labeled inhibin from the membranes. The binding was sensitive to heat and trypsin treatments. The data are consistent with the direct action of inhibin on the pituitary and demonstrate the existence of binding sites for the active fraction in this target.
Databáze: OpenAIRE