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An automated assay for the quantitative determination of the inactive dephosphorylated-uncarboxylated (dp-uc) isoform of Matrix Gla-Protein (MGP) in human plasma.  Measurement of dp-ucMGP are used the assessment of vitamin K status in the arterial vessel wall.

Matrix Gla-Protein (MGP) is the most potent inhibitor of tissue calcification presently known. MGP is a ɣ-carboxylated 11 kDa protein, comprised of 84 amino acids, which is mainly expressed and secreted by chondrocytes and vascular smooth muscle cells in the arterial media.¹ Vitamin K serves as a co-factor for the enzyme ɣ-glutamate carboxylase that converts glutamate residues into ɣ-carboxyglutamate (Gla). These Gla-residues serve as calcium-binding groups, which are essential for the activity of all Gla-containing proteins including MGP. Besides carboxylation, MGP also undergoes post-translational serine phosphorylation during maturation. Whereas carboxylation is essential for its calcification inhibitory activity, its cellular secretion is enhanced by phosphorylation.^2,3 At least four different MGP species are formed with varying states of phosphorylation and/or carboxylation: phosphorylated carboxylated MGP (p-cGMP), phosphorylated uncarboxylated MGP (p-ucMGP), desphospho-carboxylated MGP (dp-cMGP), and desphospho-uncarboxylated MGP (dp-ucMGP). Circulating forms of MGP have no known biological function, but reflect the extent of vascular calcification and availability of Vitamin K in the vessel wall.^2,4,5

Large evidences from last two decades indicate the disturbances in mi

neral and bone metabolism in chronic kidney disease patients (CKD) link with vascular calcification (VC). VC is associated with increased cardiovascular mortality and morbidity, and is recognized as a strong and independent risk factor for cardiovascular death. Various studies described a decreased availability of vitamin K, both K1 and K2, in CKD patients. Vitamin K therapy has been shown to significantly decrease the levels of dp-ucMGP both in the general population and haemodialysis patient. Conversely, it has been documented that vitamin K antagonist (VKA) is associated with higher dp-ucMGP levels.

Vitamin K status can be assessed in two different ways: (i) by measuring vitamin K concentration in plasma or (ii) by determining the amount of inactive vitamin K-dependent proteins. The first method reflects a snapshot and is influenced by triglyceride concentrations and recent vitamin K intake. The circulating vitamin K levels give little information about the vitamin K utilization in tissue. To determine the vitamin K status in the arterial vessel wall, it is better to measure the dp-ucMGP levels.

Features and benefits

• Utilise conformation-specific monoclonal antibodies to ensure accurate dp-ucMGP circulating levels
• Correlated to the widely published lab-developed dp-ucMGP ELISA assay method
• Wide assay range suitable for Chronic Kidney Disease, Haemodialysis and Vitamin K Antagonist treated patients
• First fully automated CE marked IVD dp-ucMGP test for achieving fast and highly reproducible results for diagnostic and follow up of patients

Ordering information

IDS-iSYS InaKtif MGP (dp-u-MGP),  Reagent pack: 100 tests,  IS-4700
IDS-iSYS InaKtif MGP (dp-u-MGP),  Control set: 3 levels,  IS-4730

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References