Human phosphate binding protein

Human phosphate binding protein (HPBP), an apolipoprotein that binds inorganic phosphate in blood, was serendipitously discovered. Its three-dimensional structure and complete amino acid sequence were solved (Morales et al, 2006 Diemer et al, 2008). The conditions found to separate HPBP and PONl in vitro indicated that HPBP is strongly associated with PONl (Renault et al, 2006). Moreover, the stabilization of the active form(s) of human PONl by HPBP suggests that HPBP could be a functional chaperone for PONl (Rochu et al, 2007b, c). 

Rochu, D., Renault, F., Clery-Barraud, C., Chabriere, E., Masson P. (2007b). Stability of highly purified human paraoxonase (PONl) association with human phosphate binding protein (HPBP) is essential for preserving its active conformation (s). Biochim. Biophys. Acta 1774 874-83. 

Renault, F., Chabriere, E., Andrieu, J.P., Dublet, B., Masson, P., Rochu, D. (2006). Tandem purification of two HDL-associated partner proteins in human plasma, paraoxonase (PONl) and phosphate binding protein (HPBP) using hydroxyapatite chromatography. J. Chromatogr. B 836 15-21. 

Human saliva is supersaturated with basic calcium phosphate, to allow recalcification and protection of the dental enamel. Precipitation in the saliva is prevented by certain calcium binding proteins, which include statherin268 (a 5380 molecular weight tyrosine-rich protein that also contains many proline and glutamic acid residues), and a group of proline-rich proteins.269... 

Hoshi K, Nomura K, Sano Y, and KoshiharaY (1999) Nuclear vitamin K2 binding protein in human osteoblasts homologue to glyceraJdehyde-3-phosphate dehydrogenase. Biochemical Pharmacology S3,1631-8. 

Two immunosensors developed by O Regan et al. [89,90] have demonstrated their usefulness for the early assessment of acute myocardial infarction (AMI). Human heart fatty-acid binding protein (H-FABP) is a biochemical marker for the early assessment of AMI. The authors constructed an amperometric immunosensor for the rapid detection of H-FABP in whole blood. The sensor is based on a one-step, direct sandwich assay in which the analyte and an alkaline phosphatase (AP) labelled antibody are simultaneously added to the immobilized primary antibody, using two distinct monoclonal mouse anti-human H-FABP antibodies. The substrate p-amino-phenyl phosphate is converted to p-aminophenol by AP, and the current generated by its subsequent oxidation at +300 mV vs. Ag/AgCl is measured. The total assay time is 50 min, and the standard curve was linear between 4 and 250 ng ml . The intra- and inter-assay coefficients of variation were below 9%. No cross-reactivity of the antibodies was found with other early cardiac markers, and endogenous substances in whole blood did not have an... 

Hay DI, Schluckebier SK, Moreno EC Equilibrium dialysis and ultrafiltration studies of calcium and phosphate binding by human salivary proteins. Implications for salivary supersaturation with respect to calcium phosphate salts. Calcif Tissue Int 1982 34 531-538. 

Murayama, Y., Okamoto, T., Ogata, E Asano, T., liri, T., Katada, T., Ui, M., Grubb, J.H., Sly, W.S., and Nishimoto, I. (1990). Distinctive regulation of the functional linkage between the human cation-independent mannose 6-phosphate receptor and GTP-binding proteins by insulinlike growth factor 11 and mannose 6-phosphate. J. Biol. Chem. 265 17456-17462. 

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