Basic proline-rich proteins from human parotid saliva: relationships of the covalent structures of ten proteins from a single individual

Abstract

Eleven basic proline-rich proteins were purified from the parotid saliva of a single individual. The complete amino acid sequences of six of these were determined by conventional protein sequence methodology, bringing to nine the number of known primary structures of nonglycosylated basic proline-rich proteins from the same individual. The partial sequence of one additional protein is also reported. All of the basic proline-rich proteins studied contain segments with identical or very similar sequences, but with two possible exceptions, none of the proteins is derived from another secreted proline-rich protein. The amino acid sequences of nine nonglycosylated basic proline-rich proteins were compared with primary structures deduced from published nucleotide sequences of DNA coding for human parotid proline-rich proteins. The sequences align well, in general, but differences also exist pointing to the complexity of the genetics of these proteins. Seven secretory basic proline-rich proteins appear to be formed from three larger precursors by selective posttranslational proteolyses of arginyl bonds. One of the basic proline-rich proteins appears to derive from human acidic proline-rich proteins. The remaining two proteins studied do not conform to any DNA structure as yet reported. Two of the basic proline-rich proteins studied are phosphoproteins and exhibit abilities to inhibit hydroxyapatite formation in vitro.

Trafficking and Postsecretory Events Responsible for the Formation of Secreted Human Salivary Peptides

“…4 summarizes the present knowledge of bPRP loci including coding regions for the various secreted proteins. The sequences of the majority of b-PRPs are similar and highly repetitive (26). After loss of the signal peptide, all proproteins are submitted to multiple cleavages, phosphorylation, glycosylation, and Cterminal removal (5,27,28).…”

Amino acid sequence of PR‐39

“…Other proline-rich proteins are often structural, as i n the case of collagen or the secretory protein corresponding tc the Balbiani rings of Chironomus (Wieslander et al, 1984). Proline-rich proteins have also been isolated from parotid saliva (Kauffman et al, 1991), but their function is not yet known. A common feature of most proline-rich proteins is the presence of repeated motifs.…”

Genetics of Acid Adaptation in Oral Streptococci

“…The results from a parallel study of low-molecular-weight peptides present in stimulated parotid saliva showed that there are indeed arginine-and lysine-enriched peptides in the tetra-, penta-, hexa-, and hepta-peptide size range . Comparison of sequences indicated the strong likelihood that the small peptides were derived from the salivary histatins (Troxler et al, 1990), acid proline-rich proteins (Hay et al, 1988), basic proline-rich proteins (Kauffman et al, 1991), and statherins (Jensen et al, 1991) via the action of proteases present in the salivary glands or ducts. In addition to the likelihood of host-mediated proteolysis, Streptococcus mitis (Hiraoka et al, 1986) and S. sanguis (Cowman et al, 1983;Rogers et al, 1988) produce arginine aminopeptidases.…”