Displacement of apolipophorin III from the surface of low density lipophorin by human apolipoprotein A-I.
A hybrid low density lipophorin particle (LDLp) was prepared by incubation with human apolipoprotein (apo) A-I in vitro. ApoA-I associated with LDLp in a concentration dependent, saturable manner which was accompanied by dissociation of apolipophorin III (apoLp-III). The apoA-I hybrid LDLp had the same lipid composition, density and morphology as native LDLp indicating that displacement of apoLp-III by apoA-I did not affect its structural properties. The molar ratio of apoLp-I:apoLp-II:apoLp-III was maximally reduced from 1:1:16 to 1:1:2 in native versus hybrid LDLp with the latter particle binding 7 molecules of apoA-I. The inability of apoA-I to displace the remaining 2 apoLp-III supports the concept that these apoLp-III molecules are not equivalent to the other fourteen. Native and hybrid LDLp particles were both metabolized to high density lipophorin in vivo. The displacement reaction represents a novel method for the production of apolipoprotein hybrids of LDLp and the results indicate that apoA-I has an inherently higher affinity for lipid surfaces than apoLp-III.
Liu
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Department of Biochemistry, University of Alberta, Edmonton, Canada.
Malhotra
V
V
Ryan
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RO
D000818:Animals; D016632:Apolipoprotein A-I; D001053:Apolipoproteins / Q000378:metabolism*; D001054:Apolipoproteins A / Q000378:metabolism*; D002352:Carrier Proteins / Q000378:metabolism*; D002499:Centrifugation, Density Gradient; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D007313:Insecta; D008074:Lipoproteins; D008075:Lipoproteins, HDL / Q000378:metabolism*; D008077:Lipoproteins, LDL / Q000378:metabolism
D016632:Apolipoprotein A-I; D001053:Apolipoproteins; D001054:Apolipoproteins A; D002352:Carrier Proteins; D008074:Lipoproteins; D008075:Lipoproteins, HDL; D008077:Lipoproteins, LDL; C042470:apolipophorin III; C032830:lipophorin