Basic salivary proline-rich protein 3 (PRB3)

Basic salivary proline-rich protein 3 (PRB3) is a human salivary glycoprotein encoded by the PRB3 gene, located on chromosome 12p13 in a cluster with other proline-rich proteins. PRB3 is a major constituent of parotid saliva, notable for its high proline content and substantial inter-individual allelic variation. Its primary biological role is believed to be protection of the oral cavity, particularly through binding dietary polyphenols and facilitating the formation of oral pellicle. PRB3 can act as a bacterial receptor (not a pharmacological receptor), such as for Fusobacterium nucleatum, mediating bacterial adhesion in the mouth. There is some association with head and neck cancers based on gene studies, but PRB3 is not recognized as a direct therapeutic target and there are no known drug interactions or mechanisms of action targeting this molecule. Some evidence links low PRB3 mRNA levels to resistance in prolactinoma therapy, though clinical relevance is uncertain. Overall, PRB3 is best classified as a structural and functional component of saliva rather than a classic drug target.

Other names

Proline rich protein BstNI subfamily 3PRB3PRGParotid salivary glycoprotein G1Proline-rich protein G1G1BstNI type basic salivary proline-rich protein 3G1 parotid salivary glycoproteinPRG, basic salivary proline-rich protein 3