This gene encodes a member of the heterogeneous family of basic, proline-rich, human salivary glycoproteins. Multiple alleles of this gene exhibiting variations in the length of the tandem repeats have been identified. The reference genome encodes the 'Long' allele. The protein isoforms encoded by this gene are recognized as the 'first line of oral defense' against the detrimental effects of polyphenols in the diet and pathogen infections. This gene is located in a cluster of closely related salivary proline-rich proteins on chromosome 12. [provided by RefSeq, Nov 2015].