, Volume 10, Issue 2, pp 167–169 | Cite as

The relaxin-like factor is a hormone

  • Erika E. Büllesbach
  • Richard Rhodes
  • Barbara Rembiesa
  • Christian Schwabe


The relaxin-like factor (RLF) circulates in the blood-stream of humans, interacts with a membrane protein with all the characteristics of ligand-receptor binding, and must therefore be considered a hormone by definition. The polyclonal antibody raised against synthetic human RLF showed no crossreactivity to other structurally related hormones, like insulin and relaxin. The sensitivity of this assay (ED50 at 100 pM) allowed the direct measurement of RLF concentrations in serum. The highest levels were detected in the serum of postpuberty males (190 pM), whereas in females and children, the RLF concentration was one order of magnitude lower.

Key Words

Relaxin-like factor RLF Leydig insulin-like peptide radioimmunoassay puberty 


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  1. 1.
    Adham, I. M., Burkhardt, E., Benahmed, M., and Engel, W. (1993) J. Biol. Chem. 268, 26,668–26,672.Google Scholar
  2. 2.
    Burkhardt, E., Adham, I. M., Brosig, B., Gastmann, A., Mattei, M. G., and Engel, W. (1994), Genomics 20, 13–19.PubMedCrossRefGoogle Scholar
  3. 3.
    Tashima, L. S., Hieber, A. D., Greenwood, F. C., and Bryant Greenwood, G. D. (1995). J. Clin. Endocrinol. Metab. 80, 707–710.PubMedCrossRefGoogle Scholar
  4. 4.
    Pusch, W., Balvers, M., and Ivell, R. (1996). Endocrinology 137, 3009–3013.PubMedCrossRefGoogle Scholar
  5. 5.
    Zimmermann, S., Schottler, P., Engel, W., and Adham I. M. (1997). Mol. Reprod. Develop. 47, 30–38.CrossRefGoogle Scholar
  6. 6.
    Bathgate, R., Balvers, M., Hunt, N., and Ivell, R. (1996). Biol. Reprod. 55, 1452–1457.PubMedCrossRefGoogle Scholar
  7. 7.
    Roche, P. J., Butkus, A., Wintour, E. M., and Tregear, G. (1996), Mol. Cell. Endocrinol. 121, 171–177.PubMedCrossRefGoogle Scholar
  8. 8.
    Büllesbach, E. E., and Schwabe, C. (1995), J. Biol. Chem. 370, 16,011–16,015.Google Scholar
  9. 9.
    Ivell, R., Balvers, M., Domagalski, R., Ungefroren, H., Hunt, N., and Schulze, W. (1997), Mol. Human Rep. 3, 459–466.CrossRefGoogle Scholar
  10. 10.
    Adham, I. M., Zimmermann, S., and Engel, W. (1997). Reprod. Domestic Animals 32, 73.Google Scholar
  11. 11.
    Büllesbach, E. E., and Schwabe, C. (1991), J. Biol. Chem. 266, 10,754–10,761.Google Scholar
  12. 12.
    Axén, R., Porath, J., and Ernbäck, S. (1967). Nature 214, 1302–1304.PubMedCrossRefGoogle Scholar
  13. 13.
    Wilchek, M., Miron, T., and Kohn, J. (1984). Meth. Enzymol. 104, 3–55.PubMedCrossRefGoogle Scholar
  14. 14.
    O'Byrne, E. M., Carriere, B. T., Sorensen, L., Segaloff, A., Schwabe, C., and Steinetz, B. G. (1978), J. Clin. Endocrinol. Metabol. 47, 1106–1110.CrossRefGoogle Scholar
  15. 15.
    Bell, R. J., Eddie, L. W., Lester, A. R., Wood, E. C., Johnston, P. D., and Niall, H. D. (1987) Obstet. Gynecol. 69, 585–589.PubMedGoogle Scholar

Copyright information

© Humana Press Inc 1999

Authors and Affiliations

  • Erika E. Büllesbach
    • 1
  • Richard Rhodes
    • 1
  • Barbara Rembiesa
    • 1
  • Christian Schwabe
    • 1
  1. 1.Department of Biochemistry and Molecular BiologyMedical University of South CarolinaCharleston

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