Membrane-associated proteins with specific binding properties to modified L
DL were investigated in J774 macrophages and Mono Mac 6 sr cells. Ligand bl
otting of membrane proteins revealed a 54-kDa protein which bound oxidized
and acetylated but not native LDL. The 54-kDa protein, isolated by SD-PAGE,
was identified as vimentin. I-125-AcLDL bound to purified vimentin and des
min in a saturable manner, with an. approximate K-d of 1.7 x 10(-7) M (89 m
u g/ml) and 8.0 x 10(-8) M (41 mu g/ml), respectively. Blots of vimentin mu
tant proteins with deletions in the positively charged N-terminal head doma
in showed that amino acids 26 -39 are essential for the binding of AcLDL by
vimentin. Taken together, our data indicate that vimentin binds modified L
DL, but not native LDL, in a specific and saturable manner. Vimentin filame
nts extend throughout the cytoplasm as far as the inner surfaces of plasma
and vesicular membranes. Vimentin may thus play a role in membrane-associat
ed steps involved in the intracellular processing of oxidized LDL, contribu
ting to its unregulated uptake and intracellular retention by cells of the
atherogenic plaque. (C) 2000 Academic Press.