title: Trafficking and postsecretory events responsible for the formation of secreted human salivary peptides: a proteomics approach.
abstract: To elucidate the localization of post-translational modifications of different classes of human salivary proteins and peptides (acidic and basic proline-rich proteins (PRPs), Histatins, Statherin, P-B peptide, and "S type" Cystatins) a comparative reversed phase HPLC-ESI-MS analysis on intact proteins of enriched granule preparations from parotid and submandibular glands as well as parotid, submandibular/sublingual (Sm/Sl), and whole saliva was performed. The main results of this study indicate the following. (i) Phosphorylation of all salivary peptides, sulfation of Histatin 1, proteolytic cleavages of acidic and precursor basic PRPs occur before granule storage. (ii) In agreement with previous studies, basic PRPs are secreted by the parotid gland only, whereas all isoforms of acidic PRPs (aPRPs) are secreted by both parotid and Sm/Sl glands. (iii) Phosphorylation levels of aPRPs, Histatin 1, and Statherin are higher in the parotid gland, whereas the extent of cleavage of aPRP is higher in Sm/Sl glands. (iv) O-Sulfation of tyrosines of Histatin 1 is a post-translational modification specific for the submandibular gland. (v) The concentration of Histatin 3, Histatin 5, and Histatin 6, but not Histatin 1, is higher in parotid saliva. (vi) Histatin 3 is submitted to the first proteolytic cleavage (generating Histatins 6 and 5) during granule maturation, and it occurs to the same relative extent in both glands. (vii) The proteolytic cleavages of Histatin 5 and 6, generating a cascade of Histatin 3 fragments, take place after granule secretion and are more extensive in parotid secretion. (viii) Basic PRPs are cleaved in the oral cavity by unknown peptidases, generating various small proline-rich peptides. (ix) C-terminal removal from Statherin is more extensive in parotid saliva. (x) P-B peptide is secreted by both glands, and its relative quantity is higher in submandibular/sublingual secretion. (xi) In agreement with previous studies, S type Cystatins are mainly the product of Sm/Sl glands.
authors.affiliation: Dipartimento di Scienze Applicate ai Biosistemi, Università di Cagliari, I-09042 Cagliari, Italy.
authors.forename: Irene
authors.initials: I
authors.lastname: Messana
authors.forename: Tiziana
authors.initials: T
authors.lastname: Cabras
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Pisano
authors.forename: Maria Teresa
authors.initials: MT
authors.lastname: Sanna
authors.forename: Alessandra
authors.initials: A
authors.lastname: Olianas
authors.forename: Barbara
authors.initials: B
authors.lastname: Manconi
authors.forename: Mariagiuseppina
authors.initials: M
authors.lastname: Pellegrini
authors.forename: Gaetano
authors.initials: G
authors.lastname: Paludetti
authors.forename: Emanuele
authors.initials: E
authors.lastname: Scarano
authors.forename: Antonella
authors.initials: A
authors.lastname: Fiorita
authors.forename: Stefania
authors.initials: S
authors.lastname: Agostino
authors.forename: Alessia M
authors.initials: AM
authors.lastname: Contucci
authors.forename: Lea
authors.initials: L
authors.lastname: Calò
authors.forename: Pasqualina M
authors.initials: PM
authors.lastname: Picciotti
authors.forename: Armando
authors.initials: A
authors.lastname: Manni
authors.forename: Anders
authors.initials: A
authors.lastname: Bennick
authors.forename: Alberto
authors.initials: A
authors.lastname: Vitali
authors.forename: Chiara
authors.initials: C
authors.lastname: Fanali
authors.forename: Rosanna
authors.initials: R
authors.lastname: Inzitari
authors.forename: Massimo
authors.initials: M
authors.lastname: Castagnola
mesh_terms: D000483:Alleles; D000595:Amino Acid Sequence; D002851:Chromatography, High Pressure Liquid; D006801:Humans; D008969:Molecular Sequence Data; D010306:Parotid Gland / Q000737:chemistry / Q000378:metabolism*; D010455:Peptides / Q000032:analysis / Q000378:metabolism*; D010766:Phosphorylation; D011499:Protein Processing, Post-Translational; D021381:Protein Transport; D040901:Proteomics; D012463:Saliva / Q000737:chemistry / Q000378:metabolism*; D012471:Salivary Proteins and Peptides / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D021241:Spectrometry, Mass, Electrospray Ionization; D013431:Sulfates / Q000032:analysis
chemical_list: D010455:Peptides; D012471:Salivary Proteins and Peptides; D013431:Sulfates