Skip to main content
NCBI home page
Proceedings of the National Academy of Sciences of the United States of America logoLink to Proceedings of the National Academy of Sciences of the United States of America
. 1972 Sep;69(9):2414–2416. doi: 10.1073/pnas.69.9.2414

Biological Activity of Human Chorionic Gonadotropin Released from Testis Binding-Sites

M L Dufau 1, K J Catt 1, T Tsuruhara 1
PMCID: PMC426952  PMID: 4341694

Abstract

The effect of testicular binding of human chorionic gonadotropin upon the biological activities of the hormone was examined by comparison of the binding and activation properties of 125I-labeled gonadotropin before and after binding to rat testis in vitro. Biologically active 125I-gonadotropin taken up by rat testis was dissocated from testis binding-sites at low pH and evaluated for its ability to bind again to testis, adenylate cyclase activation, and stimulation of steroidogenesis during subsequent incubation with fresh testis. Binding to tissue receptor-sites for 4 hr did not impair the biological properties of gonadotropin, though hormone remaining in the incubation medium had reduced affinity for tissue binding-sites during subsequent incubation with rat testes. In comparison to the original preparation, 125I-labeled gonadotropin previously eluted from specific binding-sites of rat testis showed significantly increased binding activity and stimulation of cyclic AMP and testosterone release during further incubation with rat testes in vitro. The enhancement of biological activity of the eluted hormone is attributable to affinity purification of the original hormone preparation by selective uptake at receptorsites. These results demonstrate that gonadotropin is not inactivated or degraded during combination with gonadotropin receptors of rat testis.

Keywords: 125I-gonadotropin, receptors, membrane, cyclic AMP, steroidogenesis

Full text

PDF
2414

Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Catt K. J., Dufau M. L., Tsuruhara T. Radioligand-receptor assay of luteinizing hormone and chorionic gonadotropin. J Clin Endocrinol Metab. 1972 Jan;34(1):123–132. doi: 10.1210/jcem-34-1-123. [DOI] [PubMed] [Google Scholar]
  2. Catt K. J., Dufau M. L., Tsuruhara T. Studies on a radioligand-receptor assay system for luteinizing hormone and chorionic gonadotropin. J Clin Endocrinol Metab. 1971 Jun;32(6):860–863. doi: 10.1210/jcem-32-6-860. [DOI] [PubMed] [Google Scholar]
  3. Catt K. J. Radioimmunoassay with antibody-coated discs and tubes. Acta Endocrinol Suppl (Copenh) 1969;142:222–246. doi: 10.1530/acta.0.062s222. [DOI] [PubMed] [Google Scholar]
  4. Catt K. J., Tsuruhara T., Dufau M. L. Gonadotrophin binding sites of the rat testis. Biochim Biophys Acta. 1972 Aug 18;279(1):194–201. doi: 10.1016/0304-4165(72)90254-1. [DOI] [PubMed] [Google Scholar]
  5. Cuatrecasas P., Desbuquois B., Krug F. Insulin-receptor interactions in liver cell membranes. Biochem Biophys Res Commun. 1971 Jul 16;44(2):333–339. doi: 10.1016/0006-291x(71)90604-8. [DOI] [PubMed] [Google Scholar]
  6. Cuatrecasas P. Properties of the insulin receptor of isolated fat cell membranes. J Biol Chem. 1971 Dec 10;246(23):7265–7274. [PubMed] [Google Scholar]
  7. Dufau M. L., Catt K. J., Tsuruhara T. A sensitive gonadotropin responsive system: radioimmunoassay of testosterone production by the rat testis in vitro. Endocrinology. 1972 Apr;90(4):1032–1040. doi: 10.1210/endo-90-4-1032. [DOI] [PubMed] [Google Scholar]
  8. Dufau M. L., Catt K. J., Tsuruhara T. Gonadotrophin stimulation of testosterone production by the rat testis in vitro. Biochim Biophys Acta. 1971 Dec 21;252(3):574–579. doi: 10.1016/0304-4165(71)90161-9. [DOI] [PubMed] [Google Scholar]
  9. Dufau M. L., Catt K. J., Tsuruhara T. Retention of in vitro biological activities by desialylated human luteinizing hormone and chorionic gonadotropin. Biochem Biophys Res Commun. 1971 Sep;44(5):1022–1029. doi: 10.1016/s0006-291x(71)80188-2. [DOI] [PubMed] [Google Scholar]
  10. Rodbell M., Krans H. M., Pohl S. L., Birnbaumer L. The glucagon-sensitive adenyl cyclase system in plasma membranes of rat liver. 3. Binding of glucagon: method of assay and specificity. J Biol Chem. 1971 Mar 25;246(6):1861–1871. [PubMed] [Google Scholar]
  11. Steiner A. L., Kipnis D. M., Utiger R., Parker C. Radioimmunoassay for the measurement of adenosine 3',5'-cyclic phosphate. Proc Natl Acad Sci U S A. 1969 Sep;64(1):367–373. doi: 10.1073/pnas.64.1.367. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. Tsuruhara T., Van Hall E. V., Dufau M. L., Catt K. J. Ovarian binding of intact and desialytated hcg in vivo and in vitro. Endocrinology. 1972 Aug;91(2):463–469. doi: 10.1210/endo-91-2-463. [DOI] [PubMed] [Google Scholar]

Articles from Proceedings of the National Academy of Sciences of the United States of America are provided here courtesy of National Academy of Sciences

RESOURCES