Neutrophil-activating peptide-2 and melanoma growth-stimulatory activity are functional as monomers for neutrophil activation.

Abstract

Neutrophil-activating peptide-2 (NAP-2) and melanoma growth-stimulatory activity (MGSA) are members of the chemokine family of inflammatory proteins. The structures of NAP-2, determined by x-ray crystallography, and MGSA, elucidated by NMR spectroscopy, revealed a tetramer and dimer, respectively. In order to address the relevance of multimeric species to their activities on neutrophils, analogs of NAP-2 and MGSA were synthesized in which the backbone amide proton of Leu-22 in NAP-2, and Val-26 in MGSA, was substituted with the bulky methyl group (NH --> NCH3). These analogs were shown to be monomeric by sedimentation equilibrium ultracentrifugation studies and were similar to the corresponding native protein in assays for neutrophil elastase release and Ca2+ mobilization from IL-8R1 and IL-8R2 transformed cells. Sedimentation equilibrium studies of the native NAP-2 and MGSA were also carried out to address the association behavior. For NAP-2, there was no evidence for the tetramer, but an equilibrium between monomers and dimers and the dissociation constant was calculated to be 50-100 microM. Similarly, MGSA showed a monomer-dimer equilibrium with a Kd of approximately 5 microM. The data from the monomeric analogs and also the calculation of dissociation constants indicate that NAP-2 and MGSA have a tendency to associate above the concentrations required for maximal activity or for receptor activation, but at functional concentrations they are predominantly monomers.

• Authors: K Rajarathnam, C M Kay, B Dewald, M Wolf, M Baggiolini, I Clark-Lewis, B D Sykes
• Journal: The Journal of biological chemistry (J Biol Chem) Vol. 272 Issue 3 Pg. 1725-9 (Jan 17 1997) ISSN: 0021-9258 [Print] United States
• PMID: 8999852 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• CXCL1 protein, human
• Chemokine CXCL1
• Chemokines, CXC
• Chemotactic Factors
• Growth Substances
• Intercellular Signaling Peptides and Proteins
• PPBP protein, human
• Peptides
• beta-Thromboglobulin
• connective tissue-activating peptide

Topics

• Chemokine CXCL1
• Chemokines, CXC
• Chemotactic Factors (chemistry, metabolism)
• Crystallography, X-Ray
• Growth Substances (chemistry, metabolism)
• Humans
• Hydrogen-Ion Concentration
• Intercellular Signaling Peptides and Proteins
• Jurkat Cells
• Magnetic Resonance Spectroscopy
• Neutrophil Activation
• Peptides (chemistry, metabolism)
• Structure-Activity Relationship
• beta-Thromboglobulin