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It is the only known transporter capable of binding phosphate ions in the human plasma. HPBP is bound to PON1, a calcium-dependent enzyme associated to HDL (High Density Lipoprotein), another lipoprotein which enables lipids like cholesterol and triglycerides to be transported from the blood to the liver. It is the place where these lipids can be removed, reducing for example the amount of arterial cholesterol. | It is the only known transporter capable of binding phosphate ions in the human plasma. HPBP is bound to PON1, a calcium-dependent enzyme associated to HDL (High Density Lipoprotein), another lipoprotein which enables lipids like cholesterol and triglycerides to be transported from the blood to the liver. It is the place where these lipids can be removed, reducing for example the amount of arterial cholesterol. | ||
HPBP is always copurified with the enzyme paraoxonase (PON1), that is why it was always ignored before 2006. The copurification is the result of a similar molecular weight, strong hydrophobic interactions, and the fact that PON1 is a glycosylated protein. The separation of the two molecules involves a hydroxyapatite chromatography with phosphate concentration gradient elution.<ref>PMID:16595195</ref><ref>PMID:19336040</ref> | HPBP is always copurified with the enzyme paraoxonase (PON1), that is why it was always ignored before 2006. The copurification is the result of a similar molecular weight, strong hydrophobic interactions, and the fact that PON1 is a glycosylated protein. The separation of the two molecules involves a hydroxyapatite chromatography with phosphate concentration gradient elution.<ref>PMID:16595195</ref><ref>PMID:19336040</ref> | ||
Up to now, HPBP has never been characterized or predicted from nucleic acid databases of human genome. Its X-ray structure is similar to the prokaryotic phosphate solute binding proteins (SBPs) associated with ATP binding cassette transmembrane transporters. Their role is to enable the unidirectional transport of substances trough the membrane, using ATP hydrolysis. | Up to now, HPBP has never been characterized or predicted from nucleic acid databases of human genome.<ref>PMID:18076037</ref> Its X-ray structure is similar to the prokaryotic phosphate solute binding proteins (SBPs) associated with ATP binding cassette transmembrane transporters. Their role is to enable the unidirectional transport of substances trough the membrane, using ATP hydrolysis. | ||
== '''Activity and physiological functions''' == | == '''Activity and physiological functions''' == | ||