HUMAN SALIVARY ACIDIC PROLINE-RICH PROTEIN POLYMORPHISMS AND BIOSYNTHESIS STUDIED BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY

Human salivary acidic proline-rich proteins (PRPs) constitute a signif icant fraction of the total salivary protein and possess important bio logical activities. Different genetic and post-translationally process ed forms of the PRPs exhibit significant quantitative variations in se veral of these activities, especially the modulation of salivary calci um phosphate chemistry and oral bacterial adhesion. To quantify and un derstand these differences, we have developed a high-performance liqui d chromatography (HPLC) method to identify and measure individual PRPs in saliva. The data obtained permit the identification of PRP polymor phisms and phenotypes, the determination of the relative amounts of PR Ps derived from the two loci, PRH1 and PRH2, and the measurement of th e extent of post-translational cleavage of the primary polypeptide pro ducts. Substantial inter-gland and interindividual variations were fou nd in relative amounts of PRPs derived from the two loci (at least two -fold), and in post-translational cleavage (greater than two-fold), bo th of which are likely to be biologically significant. Also in this st udy, the presence of what appear to be minor amounts of numerous varia nt PRPs in glandular secretions was observed, and two uncommon PRP pol ymorphisms were identified in the 127 subjects studied.