title: Human high density lipoprotein (HDL3) binding to rat liver plasma membranes.
abstract: The binding of human 125I-labeled HDL3 to purified rat liver plasma membranes was studied. 125I-labeled HDL3 bound to the membranes with a dissociation constant of 10.5 micrograms protein/ml and a maximum binding of 3.45 micrograms protein/mg membrane protein. The 125I-labeled HDL3-binding activity was primarily associated with the plasma membrane fraction of the rat liver membranes. The amount of 125I-labeled HDL3 bound to the membranes was dependent on the temperature of incubation. The binding of 125I-labeled HDL3 to the rat liver plasma membranes was competitively inhibited by unlabeled human HDL3, rat HDL, HDL from nephrotic rats enriched in apolipoprotein A-I and phosphatidylcholine complexes of human apolipoprotein A-I, but not by human or rat LDL, free human apolipoprotein A-I or phosphatidylcholine vesicles. Human 125I-labeled apolipoprotein A-I complexed with egg phosphatidylcholine bound to rat liver plasma membranes with high affinity and saturability, and the binding constants were similar to those of human 125I-labeled HDL3. The 125I-labeled HDL3-binding activity of the membranes was not sensitive to pronase or phospholipase A2; however, prior treatment of the membranes with phospholipase A2 followed by pronase digestion resulted in loss of the binding activity. Heating the membranes at 100 degrees C for 30 min also resulted in an almost complete loss of the 125I-labeled HDL3-binding activity.
mesh_terms: D000818:Animals; D001665:Binding Sites; D002462:Cell Membrane / Q000378:metabolism; D004492:Edetic Acid / Q000494:pharmacology; D004910:Erythrocyte Membrane / Q000378:metabolism; D006358:Hot Temperature; D006801:Humans; D007700:Kinetics; D008075:Lipoproteins, HDL / Q000097:blood / Q000302:isolation & purification / Q000378:metabolism*; D053440:Lipoproteins, HDL3; D008099:Liver / Q000378:metabolism*; D008297:Male; D051381:Rats; D011916:Rats, Inbred F344
chemical_list: D008075:Lipoproteins, HDL; D053440:Lipoproteins, HDL3; D004492:Edetic Acid