Proteomic analysis of polymeric salivary mucins: No evidence for MUC19 in human saliva
Résumé
MUC5B is the predominant polymeric mucin in human saliva (Thornton, Khan, Mehrotra, Howard, Veerman, Packer, and Sheehan (1999) Glycobiology 9, 293-302) where it contributes to oral cavity hydration and protection. More recently the gene for another putative polymeric mucin, MUC19, has been shown to be expressed in human salivary glands (Chen, Zhao, Kalaslavadi, Hamati, Nehrke, Le, Ann, and Wu, (2004) Am.J.Respir.Cell Mol.Biol. 30, 155-165). However, to date, the MUC19 mucin has not been isolated from human saliva. Our aim was therefore to purify and characterize the MUC19 glycoprotein from human saliva. Saliva was solubilised in 4M guanidinium chloride and the high-density mucins were purified by density gradient centrifugation. The presence of MUC19 was investigated using tandem mass spectrometry of tryptic peptides derived from this mucin preparation. Using this approach we found multiple MUC5B-derived tryptic peptides but were unable to detect any putative MUC19 peptides. These data suggest that MUC19 is not a major component in human saliva. In contrast, using the same experimental approach we identified Muc19 and Muc5b glycoproteins in horse saliva. Moreover, we also identified Muc19 from pig, cow and rat saliva; the saliva of cow and rat also contained Muc5b, although, due to the lack of pig Muc5b genomic sequence data, we were unable to identify Muc5b in pig saliva. Our data suggest that unlike human saliva which contains MUC5B, cow, horse and rat saliva is a heterogeneous mixture of Muc5b and Muc19. The functional consequence of these species differences remains to be elucidated.
Origine : Fichiers produits par l'(les) auteur(s)
Loading...