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Binding of acetylated low density lipoprotein and maleylated bovine serum albumin to the rat liver: one or two receptors?
Author(s) -
Dresel H.A.,
Friedrich E.,
Via D.P.,
Sinn H.,
Ziegler R.,
Schettler G.
Publication year - 1987
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1002/j.1460-2075.1987.tb04757.x
Subject(s) - bovine serum albumin , dissociation constant , lipoprotein , biology , serum albumin , receptor , biochemistry , scavenger receptor , binding constant , binding site , low density lipoprotein , ldl receptor , ligand binding assay , microbiology and biotechnology , chromatography , chemistry , cholesterol
The liver is the major organ involved in clearance of acetylated low density lipoprotein (acetyl‐LDL) and maleylated serum albumin (Mal‐BSA). Quantitative analysis of the hepatic uptake by sequential scintigraphy in rats shows that the hepatic uptake capacity for Mal‐BSA is at least 15 times larger than for acetyl‐LDL particles. A membrane‐associated M approximately 250,000 daltons hepatic receptor for acetyl‐LDL and Mal‐BSA was 1450‐fold purified from total membrane by Triton X‐114 solubilization, chromatography on polyethylenimine cellulose and gel filtration. This receptor incorporated into liposomes displayed a saturable binding of [131I]Mal‐BSA with a dissociation constant Kd = 15 nM and to [131I]acetyl‐LDL with a dissociation constant Kd = 0.9 nM. The binding of both ligands was sensitive to poly(vinyl sulfate). The purified scavenger receptor system has a binding capacity for [131I]Mal‐BSA 20 times larger than for [131I]acetyl‐LDL. This is similar to the maximal removal capacity of the rat liver for both ligands in vivo. Binding studies with Mal‐BSA, acetyl‐LDL and anti‐idiotypic receptor antibodies as competitors for [131I]Mal‐BSA and [131I]acetyl‐LDL binding demonstrate that [131I]Mal‐BSA and [131I]acetyl‐LDL compete for a common binding site. However, not all of the Mal‐BSA binding sites are capable of interacting with acetyl‐LDL.