Basic salivary proline-rich protein 4 (PRB4)

Basic salivary proline-rich protein 4 (PRB4) is a highly proline- and glycine-rich, intrinsically disordered salivary glycoprotein secreted predominantly by the human parotid gland. After proteolytic processing, PRB4 generates multiple mature peptides including Protein N1, Glycosylated protein A, and Peptide P-D. Its primary function is to bind and neutralize dietary tannins, protecting against their anti-nutritional effects, and to contribute to oral lubrication and interaction with oral bacteria. PRB4 exists in multiple isoforms due to alternative splicing and allelic variation, and forms part of a larger gene cluster for salivary proline-rich proteins on chromosome 12. Though associated with head and neck cancer and multiple synostoses syndrome 3 at the gene level, direct functional links to disease pathology are not established. The protein is not a recognized therapeutic target or biomarker, and there are no drugs known to act on it.

Other names

Protein N1Glycosylated protein APeptide P-DProline-rich peptide IB-5Salivary proline-rich protein PoParotid o proteinSalivary proline-rich protein II-1Pobasic salivary proline-rich protein 4BstNI type basic salivary proline-rich protein 4parotid o proteinsalivary proline-rich protein II-1salivary proline-rich protein Po