Scavenger function of sinusoidal liver cells. Acetylated low-density lipoprotein is endocytosed via a route distinct from formaldehyde-treated serum albumin.
Chemically modified proteins such as acetylated low-density lipoprotein (acetyl-LDL) and formaldehyde-treated serum albumin (f-Alb) infused intravenously are known to undergo receptor-mediated endocytosis by sinusoidal liver cells, major intravascular scavenger cells in vivo. The aim of the present study was to elucidate whether the endocytic uptake of acetyl-LDL and f-Alb is mediated by the same receptor or not. Experiments on the binding of 125I-acetyl-LDL to isolated rat liver sinusoidal cells revealed the presence of a specific, high-affinity, saturable, membrane-associated receptor with an apparent Kd = 7 micrograms of the ligand at 0 degrees C. Unlabeled acetyl-LDL effectively inhibited 125I-f-Alb binding to the cells. By contrast, the binding of 125I-acetyl-LDL to the cells was affected neither by unlabeled f-Alb nor by the antibody raised against the f-Alb receptor. These results indicate that the scavenger receptors for these two ligands are distinct from each other but similarly sensitive to polyanionic compounds.
Horiuchi
S
S
Takata
K
K
Maeda
H
H
Morino
Y
Y
D000818:Animals; D001667:Binding, Competitive; D015815:Cell Adhesion Molecules; D002462:Cell Membrane / Q000378:metabolism; D004705:Endocytosis; D005557:Formaldehyde / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D008077:Lipoproteins, LDL / Q000378:metabolism*; D008099:Liver / Q000502:physiology*; D008264:Macrophages / Q000502:physiology*; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D017457:Receptors, Albumin; D011956:Receptors, Cell Surface / Q000378:metabolism*; D011973:Receptors, LDL / Q000378:metabolism*; D051116:Receptors, Scavenger; D012710:Serum Albumin, Bovine / Q000378:metabolism*
D015815:Cell Adhesion Molecules; D008077:Lipoproteins, LDL; D017457:Receptors, Albumin; D011956:Receptors, Cell Surface; D011973:Receptors, LDL; D051116:Receptors, Scavenger; C044105:formaldehyde-serum albumin; C044106:formaldehyde-serum albumin receptor; D005557:Formaldehyde; D012710:Serum Albumin, Bovine