Ys. Kuzmenko et al., CHARACTERIZATION OF AN ATYPICAL LIPOPROTEIN-BINDING PROTEIN IN HUMAN AORTIC MEDIA MEMBRANES BY LIGAND BLOTTING, Biochemical journal, 303, 1994, pp. 281-287
By use of ligand-blotting techniques, this study investigated lipoprot
ein-binding proteins in human aortic smooth muscle. PAGE was performed
under non-reducing conditions, and, using low-density lipoprotein (LD
L) as ligand, with rabbit anti-apolipoprotein (ape) B and I-125-labell
ed goat anti-rabbit IgG as primary and secondary antibodies respective
ly, we demonstrate that membranes from human aortic media (and culture
d human smooth-muscle cells) contain a major lipoprotein-binding prote
in with an apparent molecular mass of 105 kDa. Anionized preparations
(carbamoyl- and acetyl-) of LDL, which did not displace I-125-LDL boun
d to the apo B,E receptor of cultured fibroblasts, were also recognize
d as ligands for the 105 kDa protein in aortic media membranes. LDL bi
nding to 105 kDa protein was decreased in the presence of high density
lipoprotein (HDL), although more than 100-fold molar excess of HDL wa
s required to achieve 50 % displacement of bound LDL. The LDL-binding
activity of 105 kDa protein was inhibited by EDTA, and was also signif
icantly decreased when samples were reduced by beta-mercaptoethanol be
fore electrophoresis. Monoclonal antibodies against apo B,E receptor r
eacted with partially purified bovine adrenal apo B,E receptor, but no
t with 105 kDa protein of human aortic media membranes. The spectrum o
f properties of this vascular smooth-muscle lipoprotein-binding protei
n binding are clearly distinct from those of other previously characte
rized lipoprotein-binding molecules.