The intriguing heterogeneity of human salivary proline-rich proteins: Short title: Salivary proline-rich protein species

Massimo Castagnola, Barbara Manconi, Tiziana Cabras, Alessandra Olianas, Alberto Vitali, Claudia Desiderio, Maria Teresa Sanna, Irene Messana

Research output: Contribution to journalArticlepeer-review

30 Citations (Scopus)

Abstract

The most heterogeneous family of human salivary proteins is represented by proline-rich proteins (PRPs) divided in acidic, basic, and basic glycosylated (aPRPs, bPRPs, gPRPs). They are encoded by six genes, clustered on chromosome 12p13.2: PRH1-2 encode aPRPs, PRB1-4 encode bPRPs and gPRPs. Each gene exists in different allelic forms: two for PRH2, three for PRH1, PRB2, and PRB4, four for PRB1, and PRB3. During granule maturation, PRP proproteins undergo proteolysis by the action of convertases and carboxypeptidases. Differently from bPRPs, proteolysis of aPRPs is not complete, and, besides fragments, entire protein species are also secreted. Maturation process generates ten aPRPs (PRP-1, PRP-2, PIF-s, Db-s, Pa, PRP-3, PRP-4, PIF-f, Db-f, P-C), and at least 18 bPRPs (II-2, P-E, IB-6, Ps-1, Ps-2, IB-1, P-J, IB-8a, P-F, P-H, P-D, II-1, protein glycosylated A, CD-IIg, and Gl1-4). In addition, single nucleotide and length polymorphisms, and differentially spliced transcripts originate several natural variants. Phosphorylation, N-pyroglutaminylation, dimerization, and N-/O-glycosylation also occur during maturation, enlarging the number of protein species, further increased by proteolytic events governed by carboxy- and endo-peptidases during and after secretion, and giving rise to a huge number of small peptides. The PRP functional role is still poorly understood.
Original languageEnglish
Pages (from-to)47-56
Number of pages10
JournalJOURNAL OF PROTEOMICS
Volume134
DOIs
Publication statusPublished - 2015

Keywords

  • Acidic proline-rich proteins
  • Basic proline-rich proteins
  • N-/O-glycosylated proline-rich proteins
  • N-pyroglutaminylation
  • Phosphorylation

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