This gene encodes a precursor for proline-rich salivary proteins. This and five other genes that encode salivary proline-rich proteins (PRPs)form a PRP gene cluster in the chromosomal 12p13 region. Precursor salivary PRPs are cleaved multiple times to produce a diversity of secreted peptides. Alleles of this gene exhibit tandem repeat length variation in the coding region as well as polymorphic cleavage sites and polymorphic stop codons. Alternative splicing results in multiple transcript variants encoding distinct isoforms. [provided by RefSeq, Jul 2008]