Binding of apoA-IV-phospholipid complexes to plasma membranes of rat liver.
Rat apoA-IV complexes with dimyristoyl phosphatidylcholine (apoA-IV-DMPC) have been prepared and their ability to bind to purified rat liver plasma membranes investigated. Binding equilibrium at 37 degrees C was reached in 30 minutes. Saturation binding experiments and subsequent analysis of the results with Scatchard plots gave results consistent with the presence of a single saturable binding site. DMPC or POPC unilamellar vesicles could not compete with apoA-IV-DMPC for binding; apoA-I-DMPC competed only partially. ApoE-poor HDL effectively competed with apoA-IV-DMPC. The fact that binding could be greatly reduced (greater than 70%) by preincubating the membrane with pronase (18 micrograms/ml), supports the conclusion that a membrane protein is involved in binding. Based on these results, we speculate that the rapid catabolism of apoA-IV in plasma may be mediated by a specific uptake mechanism in the liver. The implications of these results support the hypothesis that apoA-IV is involved in reverse cholesterol transport.
D000818:Animals; D001054:Apolipoproteins A / Q000378:metabolism*; D001665:Binding Sites; D002462:Cell Membrane / Q000378:metabolism; D002784:Cholesterol / Q000378:metabolism; D002788:Cholesterol Esters / Q000378:metabolism; D004134:Dimyristoylphosphatidylcholine / Q000378:metabolism*; D066298:In Vitro Techniques; D008099:Liver / Q000378:metabolism*; D008297:Male; D011402:Pronase / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains
D001054:Apolipoproteins A; D002788:Cholesterol Esters; C022205:apolipoprotein A-IV; D002784:Cholesterol; D011402:Pronase; D004134:Dimyristoylphosphatidylcholine