MG2 and Lactoferrin Form a Heterotypic Complex in Salivary Secretions

• Published in: Journal of dental research Vol. 82; no. 6; pp. 471 - 475
• Main Authors: Soares, R.V., Siqueira, C.C., Bruno, L.S., Oppenheim, F.G., Offner, G.D., Troxler, R.F.
• Format: Journal Article
• Language: English
• Published: United States SAGE Publications 01.06.2003; SAGE PUBLICATIONS, INC
• Subjects: Adult; Alanine; Cysteine; Humans; Immunoglobulin A, Secretory - metabolism; Lactoferrin - metabolism; Leucine; Mucins - metabolism; Oligopeptides - chemistry; Oxidants - pharmacology; Periodic Acid - pharmacology; Protein Binding - drug effects; Protein Interaction Mapping; Salivary Proteins and Peptides - metabolism; Sequence Analysis, Protein; Species Specificity; saliva; salivary proteins; protein-protein interactions
• ISSN: 0022-0345; 1544-0591
• DOI: 10.1177/154405910308200613

Protein-protein interactions are necessary for homeostasis to be maintained and for biological systems to be integrated. Heterotypic complexes occur in saliva, and a complex between MG2 and SIgA has been suggested to promote microbial clearance from the oral cavity. In this study, we used a peptide display library to investigate previously unrecognized heterotypic complexes involving MG2 and other proteins. The library was panned with MG2 12 times, and analyses of clones identified the sequence Ala-Leu-Leu-Cys-, which occurs in salivary lactoferrin. Blotting experiments confirmed that MG2 and lactoferrin form a heterotypic complex in viro and in vivo. Periodate treatment of MG2 did not affect the interaction. A synthetic lactoferrin peptide containing the motif Ala-Leu-Leu-Cys-blocked the interaction between MG2 and lactoferrin, confirming the specificity of the interaction identified by panning. This complex may enhance the properties of these salivary components in the oral environment.