A novel beta-endorphin binding protein. Complement S protein (= vitronectin) exhibits specific non-opioid binding sites for beta-endorphin upon interaction with heparin or surfaces.

Abstract

Human beta-endorphin (1-31) (beta H-endorphin) was found to specifically interact with purified complement S protein from human plasma. As found by chemical cross-linking beta H-endorphin bound to both, the 65- and 75-kDa molecular mass forms of S protein. The interaction of S protein with heparin as well as the adsorption of S protein to surfaces led to an almost 10-fold increase of specific binding which was due to the exposure of further beta H-endorphin-binding sites. The interaction of beta H-endorphin with S protein bore characteristics of a ligand-receptor interaction, such as time dependence, reversibility, high affinity, saturability, and structural specificity and was mediated through the non-opioid COOH terminus of the beta H-endorphin molecule. beta H-Endorphin binding to S protein was observed at physiological pH or cation concentrations, indicating that the interaction may well occur in vivo. Our results provide conclusive evidence that interactions of S protein with very different effectors led to similar conformational changes which uniformly resulted in exposure of a highly specific beta H-endorphin binding domain on S protein. With S protein as major beta H-endorphin-binding protein in the periphery, the molecular basis of a widespread system of humoral target sites of the neuroendocrine effector appears to be established. In view of S protein involvement in processes of inflammation and wound repair and beta-endorphin effects on immunocompetent cells, the demonstrated S protein-beta H-endorphin interaction appears to be of considerable functional significance.

• Authors: A Hildebrand, K T Preissner, G Müller-Berghaus, H Teschemacher
• Journal: The Journal of biological chemistry (J Biol Chem) Vol. 264 Issue 26 Pg. 15429-34 (Sep 15 1989) ISSN: 0021-9258 [Print] United States
• PMID: 2475499 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Blood Proteins
• Cross-Linking Reagents
• Glycoproteins
• Glycosaminoglycans
• Peptide Fragments
• Succinimides
• Vitronectin
• beta-Endorphin
• Heparin
• disuccinimidyl suberate

Topics

• Binding Sites
• Blood Proteins (metabolism)
• Cross-Linking Reagents (pharmacology)
• Glycoproteins (isolation & purification, metabolism)
• Glycosaminoglycans (pharmacology)
• Heparin (pharmacology)
• Humans
• Kinetics
• Molecular Weight
• Peptide Fragments (metabolism)
• Succinimides (pharmacology)
• Vitronectin
• beta-Endorphin (metabolism)