Binding of β-VLDL to Heparan Sulfate Proteoglycans Requires Lipoprotein Lipase, Whereas ApoE Only Modulates Binding Affinity

The binding of β-VLDL to heparan sulfate proteoglycans (HSPG) has been reported to be stimulated by both apoE and lipoprotein lipase (LPL). In the present study we investigated the effect of the isoform and the amount of apoE per particle, as well as the role of LPL on the binding of β-VLDL to HSPG. Therefore, we isolated β-VLDL from transgenic mice, expressing either APOE*2(Arg158→Cys) or APOE*3-Leiden (E2-VLDL and E3Leiden-VLDL, respectively), as well as from apoE-deficient mice containing no apoE at all (Enull-VLDL). In the absence of LPL, the binding affinity and maximal binding capacity of all β-VLDL samples for HSPG-coated microtiter plates was very low. Addition of LPL to this cell-free system resulted in a 12- to 55-fold increase in the binding affinity and a 7- to 15-fold increase in the maximal binding capacity (B(max)). In the presence of LPL, the association constant (K(a)) tended to increase in the order Enull-VLDL

Keywords:

• Gene isoform
• Very low-density lipoprotein
• Proteoglycan
• Lipoprotein lipase
• Apolipoprotein E
• Apolipoprotein E2
• Apolipoproteins E
• Biochemistry
• Ligand (biochemistry)
• Biology

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