Inhibition of Calcium Oxalate Crystal Growth in vitro by Uropontin: Another Member of the Aspartic Acid-Rich Protein Superfamily

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 89; no. 1; pp. 426 - 430
• Main Authors: Shiraga, H., Min, W., VanDusen, W. J., Clayman, M. D., Miner, D., Terrell, C. H., Sherbotie, J. R., Foreman, J. W., Przysiecki, C., Neilson, E. G., Hoyer, J. R.
• Format: Journal Article
• Language: English
• Published: Washington, DC National Academy of Sciences of the United States of America 01-01-1992; National Acad Sciences; National Academy of Sciences
• Subjects: Amino Acid Sequence; Amino acids; Antibodies, Monoclonal; aspartic acid; Aspartic Acid - chemistry; Biological and medical sciences; Calcium; Calcium Oxalate - chemistry; Cell physiology; Crystal growth; Crystallization; Crystals; Enzyme linked immunosorbent assay; Fundamental and applied biological sciences. Psychology; Humans; Medical disorders; Medical research; Mineralization, calcification; Molecular and cellular biology; Molecular Sequence Data; Monoclonal antibodies; Multigene Family; Osteopontin; Oxalates; Proteins; Proteins - chemistry; Proteins - immunology; Reactivity; Sequence Alignment; Sialoglycoproteins - chemistry; Sialoglycoproteins - immunology; Sialoglycoproteins - urine; Urinary Bladder Calculi - chemistry; Urine; Urology; uropontin; Crystal growth; Human; Urine; Mineralization; Organic salt; Inhibition; Urinary stone
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.89.1.426

The majority of human urinary stones are primarily composed of calcium salts. Although normal urine is frequently supersaturated with respect to calcium oxalate, most humans do not form stones. Inhibitors are among the multiple factors that may influence the complex process of urinary stone formation. We have isolated an inhibitor of calcium oxalate crystal growth from human urine by monoclonal antibody immunoaffinity chromatography. The N-terminal amino acid sequence and acidic amino acid content of this aspartic acid-rich protein, uropontin, are similar to those of other pontin proteins from bone, plasma, breast milk, and cells. The inhibitory effect of uropontin on calcium oxalate crystal growth in vitro supports the concept that pontins may have a regulatory role. This function would be analogous to that of other members of the aspartic acid-rich protein superfamily, which stereospecifically regulate the mineralization fronts of calcium-containing crystals.