The Relaxin-Like Factor

  • Christian Schwabe
  • Erika E. Büllesbach


Testicular Leydig cells contain the message for a protein of the insulin/relaxin-like family which, in the heat of discovery, was called the Leydig insulin-like peptide (LEY I-L)1 or INSL3, corresponding to the chromosomal location of the human gene.2 The authors felt that this was a Leydig cell specific message and predicted an insulin-like character for the gene product.1 Upon close scrutiny one will notice that the critical position in the A chain-loop, which decides between insulin or relaxin-like conformations, was occupied by glycine (relaxin configuration) instead of isoleucine (insulin configuration). Furthermore, the cDNA sequence of the B-chain also showed more relaxin-like characteristics, in particular the binding-site sequence RXXXR which occurred four residues further toward the C-terminal end of the molecule (Fig. 16.1). This meant a displacement of exactly one helix turn with the arginines still projecting essentially away from the core as they do in relaxin. All this was enough reason to synthesize the molecule according to the cDNA sequence and to study its physicochemical and biological properties. Within a month this new factor was synthesized and measurements of circular dichroism as a function of wavelength showed a conformation very similar to that of porcine relaxin.3 A tracer was produced by direct iodination of a synthetic precursor as given below.


High Performance Liquid Chromatography Leydig Cell Symphysis Pubis Methionine Sulfoxide Germ Cell Death 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. 1.
    Adham IM, Burkhardt E, Benahmed M et al. Cloning of a cDNA for a novel insulin-like peptide of the testicular Leydig cells. J Biol Chem 1993; 268: 26668 - 26672PubMedGoogle Scholar
  2. 2.
    Burkhardt E, Adham IM, Brosig B et al. Structural organization of the porcine and human genes coding for a Leydig cell-specific insulin-like peptide (LEY I-L) and chromosomal localization of the human gene (INSL3). Genomics 1994; 20: 13 - 19.PubMedCrossRefGoogle Scholar
  3. 3.
    Büllesbach EE, Schwabe C. A novel Leydig cell cDNA-derived protein is a relaxin-like factor (RLF). J Biol Chem 1995; 370: 16011 - 16015.Google Scholar
  4. 4.
    Tashima LS, Hieber AD, Greenwood FC et al. The human Leydig insulin-like (hLey i-1) gene is expressed in the corpus luteum and trophoblast. J Clin Endocrinol Metab 1995; 80: 707 - 710.PubMedCrossRefGoogle Scholar
  5. 5.
    Zimmermann S, Schottler P, Engel W et al. Mouse Leydig insulin-like (Ley I-L) gene—Structure and expression during testis and ovary development. Mol Reprod Develop 1997; 47: 30 - 38.CrossRefGoogle Scholar
  6. 6.
    Bathgate R, Balvers M, Hunt N et al. Relaxin-like factor gene is highly expressed in the bovine ovary of the cycle and pregnancy—Sequence and messenger ribonucleic acid analysis. Biol Reprod 1996; 551452-1457.Google Scholar
  7. 7.
    Roche PJ, Butkus A, Wintour EM et al. Structure and expression of Leydig insulin-like peptide mRNA in the sheep. Mol Cell Endocrinology 1996; 121: 171 - 177.CrossRefGoogle Scholar
  8. 8.
    Plunkett MJ, Ellman JA. Combinatorial Chemistry and New Drugs. Scientific American 1997; 276: 68 - 73.PubMedCrossRefGoogle Scholar
  9. 9.
    Hogan JC. Combinatorial Chemistry In Drug Discovery. Nature Biotechnology 1997; 15: 328 - 330.PubMedCrossRefGoogle Scholar
  10. 10.
    Burkhardt E, Adham IM, Hobohm U et al. A human cDNA coding for the Leydig insulin-like peptide (LEY I-L). Hum Genet 1994; 94: 91 - 94.PubMedCrossRefGoogle Scholar
  11. 11.
    Pusch W, Balvers M, Ivell R. Molecular cloning and expression of the relaxin-like factor from the mouse testis. Endocrinology 1996; 137: 3009 - 3013.PubMedCrossRefGoogle Scholar
  12. 12.
    Adham IM, Zimmermann S, Engel W. Leydig insulin-like hormone-deficient mice show male premeiotic arrest and germ cell death. Reprod Domestic Animals 1997; 32: 73.Google Scholar
  13. 13.
    Yang S, Rembiesa B, Büllesbach EE et al. Relaxin receptors in mice: Demonstration of ligand binding in symphyseal tissues and uterine membrane. Endocrinology 1992; 130: 179 - 185.PubMedCrossRefGoogle Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 1998

Authors and Affiliations

  • Christian Schwabe
    • 1
  • Erika E. Büllesbach
    • 1
  1. 1.Medical University of South CarolinaCharlestonUSA

Personalised recommendations