Calcified Tissue International

, Volume 50, Issue 5, pp 391–396 | Cite as

Acidic phosphoproteins from bone matrix: A structural rationalization of their role in biomineralization

  • Jeffrey P. Gorski


Osteopontin, bone sialoprotein, and bone acidic glycoprotein-75 are three acidic phosphoproteins that are isolated from the mineralized phase of bone matrix, are synthesized by osteoblastic cells, and are generally restricted in their distribution to calcified tissues. Although each is a distinct gene product, these proteins share aspartic/glutamic acid contents of 30–36% and each contains multiple phosphoryl and sialyl groups. These properties, plus a strict relationship of acidic macromolecules with cell-controlled mineralization throughout nature, suggest functions in calcium binding and nucleation of calcium hydroxyapatite crystal formation. However, direct proof for such roles is still largely indirect in nature. The purpose of this review is to present two speculative hypotheses regarding acidic phosphoprotein function. The goal was to use new sequence information along with database comparisons to develop a structural rationalization of how these proteins may function in calcium handling by bone. For example, our analysis has identified a conserved polyacidic stretch in all three phosphoproteins which we propose mediates metal binding. Also, conserved motifs were identified that are analogous with those for casein kinase II phosphorylation sites and whose number correlates well with that of phosphoryl groups/protein. A two-state conformational model of calcium binding by bone matrix acidic phosphoproteins is described which incorporates these findings.

Key words

Bone Matrix Phosphoproteins Biomineralization Calcium Nucleation 


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  1. 1.
    Fisher LW, Whitson SW, Avioli LV, Termine JD (1983) Matrix sialoprotein of developing bone. J Biol Chem 258:12723–12727Google Scholar
  2. 2.
    Franzen A, Heinegard D (1985) Isolation and characterization of two sialoproteins present only in bone calcified matrix. Biochem J 232:715–724Google Scholar
  3. 3.
    Prince CW, Oosawa T, Butler WT, Tomana M, Bhown AS, Bhown M, Schrohenloher RE (1987) Isolation, characterization, and biosynthesis of a phosphorylated glycoprotein from rat bone. J Biol Chem 262:2900–2907Google Scholar
  4. 4.
    Franzen A, Heinegard D (1985) Proteoglycans and proteins of rat bone. In: Butler WT (ed) The chemistry and biology of mineralized tissues. EBSCO Media, Birmingham, AL, pp 132–141Google Scholar
  5. 5.
    Fisher LW, Hawkins GR, Tuross N, Termine JD (1987) Purification and partial characterization of small proteoglycans I and II, bone sialoproteins I and II, and osteonectin from the mineral compartment of developing human bone. J Biol Chem 262:9702–9708Google Scholar
  6. 6.
    Gorski JP, Shimizu K (1988) Isolation of new phosphorylated glycoprotein from mineralized phase of bone that exhibits limited homology to adhesive protein osteopontin. J Biol Chem 263:15938–15945Google Scholar
  7. 7.
    Gorski JP, Griffin D, Dudley G, Stanford C, Thomas R, Huang C, Lai E, Karr B, Solursh M (1990) Bone acidic glycoprotein-75 is a major synthetic product of osteoblastic cells and localized as 75- and 50-kDa forms in mineralized phases of bone and growth plate and in serum. J Biol Chem 265:14956–14963Google Scholar
  8. 8.
    Oldberg A, Franzen A, Heinegard D (1986) Cloning and sequence analysis of rat bone sialoprotein (osteopontin) cDNA reveals an Arg-Gly-Asp cell-binding sequence. Proc Natl Acad Sci USA 83:8819–8823Google Scholar
  9. 9.
    Oldberg A, Franzen A, Heinegard D (1988) The primary structure of a cell-binding bone sialoprotein. J Biol Chem 263:19430–19432Google Scholar
  10. 10.
    Boskey A (1989) Noncollagenous matrix proteins and their role in mineralization. Bone Miner 6:111–123Google Scholar
  11. 11.
    Glimcher MJ (1989) Mechanism of calcification: role of collagen fibrils and collagen-phosphoprotein complexes in vitro and in vivo. Anat Rec 224:139–153Google Scholar
  12. 12.
    Lownstam A, Weiner S (1989) Biomineralization processes. In: On Biomineralization. Oxford University Press, London, pp 25–49Google Scholar
  13. 13.
    Bianco P, Fisher LW, Young MF, Termine JD, Gehron-Robey P (1991) Expression of bone sialoprotein (BSP) in developing human tissues. Calcif Tissue Int 49:421–426Google Scholar
  14. 14.
    Fisher LW, McBride OW, Termine JD, Young MF (1990) Human bone sialoprotein: deduced protein sequence and chromosomal location. J Biol Chem 265:2347–2351Google Scholar
  15. 15.
    Nomura S, Wills AJ, Edwards DR, Heath JK, Hogan BLM (1988) Developmental expression of 2ar (osteopontin) and SPARC (osteonectin) RNA as revealed by in situ hybridization. J Cell Biol 106:441–450Google Scholar
  16. 16.
    Mark MP, Prince CW, Gay S, Austin RL, Butler WT (1988) 44-kDal bone phosphoprotein (osteopontin) antigenicity at ectopic sites in newborn rats: kidney and nervous tissues. Cell Tissue Res 251:23–30Google Scholar
  17. 17.
    Ecarot-Charrier B, Bouchard F, Delloye C (1989) Bone sialoprotein II synthesized by cultured osteoblasts contains tyrosine sulfate. J Biol Chem 264:20049–20053Google Scholar
  18. 18.
    Yoon K, Buenaga R, Rodan GA (1987) Tissue specificity and developmental expression of rat osteopontin. Biochem Biophys Res Commun 148:1129–1136Google Scholar
  19. 19.
    Nagata T, Todescan R, Goldberg HA, Zhang Q, Sodek J (1989) Sulphation of secreted phosphoprotein I (SPPI, osteopontin) is associated with mineralized tissue formtion. Biochem Biophys Res Commun 165:234–240Google Scholar
  20. 20.
    Groot CG (1982) An electron microscopical examination for the presence of acid groups in the organic matrix of mineralization nodules in fetal bone. Metab Bone Dis Rel Res 4:77–84Google Scholar
  21. 21.
    Senger DR, Perruzzi CA, Gracey CF, Papadopoulos A, Tenen DG (1988) Secreted phosphoproteins associated with neoplastic transformation: close homology with plasma proteins cleaved during blood coagulation. Cancer Res 48:5770–5774Google Scholar
  22. 22.
    Kiefer MC, Bauer DM, Barr PJ (1989) The cDNA and derived amino acid sequence for human osteopontin. Nucleic Acids Res 17:3306Google Scholar
  23. 23.
    Wrana JL, Zhang Q, Sodek J (1989) Full length cDNA sequence of porcine-secreted phosphoprotein-I (SPP-I, osteopontin). Nucleic Acids Res 17:10119Google Scholar
  24. 24.
    Miyazaki Y, Setoguchi M, Yoshida S, Higuichi Y, Akizuki S, Yamamoto S (1989) Nucleotide sequence of cDNA for mouse osteopontin-like protein. Nucleic Acids Res 17:3298Google Scholar
  25. 25.
    Oldberg A, Franzen A, Heinegard D, Pierschbacher M, Ruoslahti E (1988) Identification of a bone sialoprotein receptor in osteosarcoma cells. J Biol Chem 263:19433–19436Google Scholar
  26. 26.
    Horton MA, Davies J (1989) Perspectives: adhesion receptors in bone. J Bone Miner Res 4:803–808Google Scholar
  27. 27.
    Frangou-Lazaridis M, Clinton M, Goodall GJ, Horecker BL (1988) Prothymosin α and parathymosin: amino acid sequences deduced from the cloned rat spleen cDNAs. Arch Biochem Biophys 263:305–310Google Scholar
  28. 28.
    Scott BT, Simmerman HKB, Collins JH, Nadal-Ginard B, Jones LR (1988) Complete amino acid sequence of canine cardiac calsequestrin deduced by cDNA cloning. J Biol Chem 263:8958–8964Google Scholar
  29. 29.
    Zarain-Herzberg A, Fliegel L, MacLennan DH (1988) Structure of the rabbit fast-twitch skeletal muscle calsequestrin gene. J Biol Chem 263:4807–4812Google Scholar
  30. 30.
    Anderegg RJ, Carr SA, Huang IY, Hiipakka RA, Chang C, Liao S (1988) Correction of the cDNA-derived protein sequence of prostatic spermine binding protein: pivotal role of tandem mass spectrometry in sequence analysis. Biochemistry 27:4214–4221Google Scholar
  31. 31.
    Gaber RF, Styles CA, Fink GR (1988) TRK1 encodes a plasma membrane protein required for high-affinity potassium transport in Saccharomyces cerevisiase. Mol Cell Biol 8:2848–2859Google Scholar
  32. 32.
    Noda M, Shimizu S, Tanabe T, Takai T, Kayano T, Ikeda T, Takahashi H, Nakayama H, Kanaoka Y, Minamino N, Kangawa K, Matsuo H, Raftery M, Hirose T, Inayama S, Hayashida H, Miyata T, Numa S (1984) Primary structure of Electrophorus electricus sodium channel deduced from cDNA sequence. Nature 312:121–127Google Scholar
  33. 33.
    Ono T, Slaughter GR, Cook RG, Means AR (1989) Molecular cloning sequence and distribution of rat calspermin, a high affinity calmodulin-binding protein. J Biol Chem 264:2081–2087Google Scholar
  34. 34.
    Clegg DO, Helder JC, Hann BC, Hall DE, Reichardt LF (1988) Amino acid sequence and distribution of mRNA encoding major skeletal muscle laminin binding protein: extracellular matrix-associated protein with unusual COOH-terminal polyaspartate domain. J Cell Biol 107:699–705Google Scholar
  35. 35.
    Maridor G, Krek W, Nigg EA (1990) Structure and developmental expression of chicken nucleolin and NO38: coordinate expression of two abundant non-ribosomal nucleolar proteins. Biochim Biophys Acta 1049:126–133Google Scholar
  36. 36.
    Van Loon APGM, DeGroot RJ, DeHann M, Kekker A, Givell LA (1984) The DNA sequence of the nuclear gene coding for the 17-kd subunit VI of the yeast ubiquinol-cytochrome c reductase: a protein with an extremely high content of acidic amino acids. EMBO J 3:1039–1043Google Scholar
  37. 37.
    Brand IA, Heinickel A, Kratzin H, Soling HD (1988) Properties of a 19-kDa Zn+2-binding protein and sequence of the Zn+2-binding domains. Eur J Biochem 177:561–568Google Scholar
  38. 38.
    Stuhmer W, Conti F, Suzuki H, Wang X, Noda M, Yahagi N, Kubo H, Numa S (1989) Structural parts involved in activation and inactivation of the sodium channel. Nature 33:597–603Google Scholar
  39. 39.
    Mitchell RD, Simmerman HKB, Jones LR (1988) Ca+2 binding effects on protein conformation and protein interactions of canine cardiac calsequestrin. J Biol Chem 263:1376–1381Google Scholar
  40. 40.
    Marshak DR, Carroll D (1991) Synthetic peptide substrates for casein kinase II. Methods Enzymol 200:134–156Google Scholar
  41. 41.
    Meggio F, Marchiori F, Borin G, Chessa G, Pinna LA (1984) Synthetic peptides including acidic clusters as substrates and inhibitors of rat liver casein kinase TS (type-2). J Biol Chem 259:14576–14579Google Scholar
  42. 42.
    Kuenzel EA, Mulligan JA, Sommercorn J, Krebs EG (1987) Substrate specificity determinants for casein kinase II as deduced from studies with synthetic substrates. J Biol Chem 262:9136–9140Google Scholar
  43. 43.
    Romberg RW, Werness PG, Lollar P, Riggs BL, Mann KG (1986) Inhibition of hydroxyapatite crystal growth by bone-specific and other calcium-binding proteins. Biochemistry 25:1176–1180Google Scholar
  44. 44.
    Chen C-C, Boskey AL, Rosenberg LC (1984) The inhibitory effect of cartilage proteoglycans on hydroxyapatite growth. Calcif Tissue Int 36:285–290Google Scholar
  45. 45.
    Cuervo LA, Pita JC, Howell DS (1973) Inhibition of calcium phosphate mineral growth by proteoglycan aggregate fractions in a synthetic lymph. Calcif Tissue Int 13:1–10Google Scholar
  46. 46.
    Hunter GK (1987) An ion-exchange mechanism of cartilage calcification. Connect Tissue Res 16:111–120Google Scholar
  47. 47.
    Blumenthal NC, Poser AS, Silverman LD, Rosenberg LC (1979) Effect of proteoglycans on in vitro hydroxyapatite formation. Calcif Tissue Int 27:75–82Google Scholar
  48. 48.
    Addadi L, Moradian J, Shay E, Maroudas NG, Weiner S (1987) A chemical model for the cooperation of sulfates and carboxylates in calcite crystal nucleation: relevance to biomineralization. Proc Natl Acad Sci USA 84:2732–2736Google Scholar
  49. 49.
    Linde A, Lussi A, Crenshaw MA (1989) Mineral induction by immobilized polyanionic proteins. Calcif Tissue Int 44:286–295Google Scholar
  50. 50.
    Pinto MR, Kelly PJ (1984) Age-related changes in bone in the dog: fluid spaces and their K+ content. J Orthop Res 2:2–7Google Scholar
  51. 51.
    Chen Y, Gorski JP (1990) Comparison of in vitro calcium-binding properties of individual extracellular phosphoproteins from bone. J Cell Biol 111:356aGoogle Scholar
  52. 52.
    Klee CB, Vanaman TC (1982) Calmodulin. Adv Protein Chem 35:213–321Google Scholar
  53. 53.
    Furie B, Furie BC (1988) The molecular basis of blood coagulation. Cell 53:505–518Google Scholar
  54. 54.
    Curley-Joseph J, Veis A (1979) The nature of covalent complexes of phosphoproteins with collagen in the bovine dentin matrix. J Dent Res 58:1625–1633Google Scholar
  55. 55.
    Veis A (1984) Bones and teeth. In: Piez KA, Reddi AH (eds) Extracellular matrix biochemistry. Elsevier, New York, pp 329–374Google Scholar
  56. 56.
    Strynadka NCJ, James MNG (1989) Crystal structures of the helix-loop-helix calcium-binding proteins. Annu Rev Biochem 58:951–998Google Scholar
  57. 57.
    Theil EC (1990) The ferritin family of iron storage proteins. Adv Enzymol 63:421–449Google Scholar
  58. 58.
    Yang C, Meagher A, Huynh BH, Sayers DE, Theil EC (1987) Iron(III) clusters bound to horse spleen apoferritin: an x-ray absorption and mossbauer spectroscopy study that shows that iron nuclei can form on the protein. Biochemistry 26:497–503Google Scholar
  59. 59.
    Wetz K, Crichton RR (1976) Chemical modificaiton as a probe of the topography and reactivity of horse-spleen apoferritin. Eur J Biochem 61:545–550Google Scholar
  60. 60.
    Wustefeld C, Crichton RR (1982) The amino acid sequence of human spleen apoferritin. FEBS Lett 150:43–48Google Scholar
  61. 61.
    Gorski JP, Bronk JT, Moyer TP (1987) Mineralization of healing canine tibial defects. In: Sen A, Thornhill T (eds) Development and diseases of cartilage and bone matrix. Alan R. Liss, New York, pp 377–387Google Scholar
  62. 62.
    Gerstenfeld LC, Chipman SD, Glowacki J, Lian JB (1987) Expression of differentiated function by mineralizing cultures of chicken osteoblasts. Dev Biol 122:49–60Google Scholar

Copyright information

© Springer-Veriag New York Inc 1992

Authors and Affiliations

  • Jeffrey P. Gorski
    • 1
  1. 1.Division of Molecular Biology and Biochemistry, School of Basic Life SciencesUniversity of Missouri-Kansas CityKansas CityUSA

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