title: Studies on primate gonadotropin receptors: characterization of the rhesus monkey testicular follicle-stimulating hormone receptors.
abstract: The properties of adult rhesus monkey testicular FSH receptor was investigated in these experiments. The interaction of 125I-labeled human FSH with a monkey testicular particulate fraction is a time- and temperature dependent phenomenon. Equilibrium of hormone-receptor interaction occurred by about 4-6 at 37 or 34 C, was slow at 25 C, and was extremely slow at 4 C. Maximum binding occurred at pH 7-7.5, with a requirement of 5-10 mM MgCl2 or CaCl2. The half-life of the receptor with exposed sites for hormone interaction was temperature related (1 h at 37 C, 1.5 h at 34 C, 6 h at 25 C, and 36 h at 4 C). Occupancy of these sites by the labeled hormone rendered the receptor more stable. The hormone-receptor complex was highly stable, as shown by the fact that excess unlabeled hormone was unable to displace the already bound labeled hormone from the receptor. Conditions unfavorable for hormone-receptor interaction, such as pH 5.0 or pH 10 or high salt concentration (0.5 M MgCl2), induced the maximum dissociation of the preformed hormone-receptor complex. The primate testis FSH receptor was inactivated by trypsin, phospholipase C, and reducing agents, but it was not influenced by nucleases. Neuraminidase treatment of the particulate receptor may have enhanced its ability to bind labeled human FSH.
mesh_terms: D000818:Animals; D006801:Humans; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D008253:Macaca mulatta; D008297:Male; D009994:Osmolar Concentration; D011956:Receptors, Cell Surface / Q000378:metabolism*; D011962:Receptors, FSH; D013696:Temperature; D013737:Testis / Q000378:metabolism*; D013997:Time Factors
chemical_list: D011956:Receptors, Cell Surface; D011962:Receptors, FSH