basic salivary proline-rich protein 2; con1 glycoprotein; contains: basic proline-rich peptide IB-1; basic proline-rich peptide P-E; IB-9 basic proline-rich peptide IB-7; basic proline-rich peptide IB-8c; basic peptide P-F; basic proline-rich peptide IB-4 (PRB2)

Function

• proteolytically cleaved at the tripeptide Xaa-Pro-Gln, where Xaa in the P(3) position is mostly Lys
• the endoprotease may be of microbial origin
• pyroglutamate formation occurs on terminal Gln of cleaved peptides
• pyroglutamate formation found on at least Gln-398 & Gln-400

Structure

• N-glycosylated & O-glycosylated

Compartment

secreted (putative)

Pathology

• in head & neck cancer patients, O-glycosylated with glucosylgalactosyl carbohydrate moiety
• this modification would require prior hydroxylation on Lys

Polymorphism

• the number of repeats is polymorphic & varies among different alleles

Notes

peptides IB-9 & P-E are the same peptide

More general terms

• salivary proline-rich protein
• phosphoprotein

Database

• OMIM: https://mirror.omim.org/entry/168810
• UniProt: http://www.uniprot.org/uniprot/P02812.html