Identification of the principal proteoglycan-binding site in LDL. A single-point mutation in apo-B100 severely affects proteoglycan interaction without affecting LDL receptor binding.
AUTOR(ES)
Borén, J
RESUMO
The subendothelial retention of LDLs through their interaction with proteoglycans has been proposed to be a key process in the pathogenesis of atherosclerosis. In vitro studies have identified eight clusters of basic amino acids in delipidated apo-B100, the protein moiety of LDL, that bind the negatively charged proteoglycans. To determine which of these sites is functional on the surface of LDL particles, we analyzed the proteoglycan-binding activity of recombinant human LDL isolated from transgenic mice. Substitution of neutral amino acids for the basic amino acids residues in site B (residues 3359-3369) abolished both the receptor-binding and the proteoglycan-binding activities of the recombinant LDL. Chemical modification of the remaining basic residues caused only a marginal further reduction in proteoglycan binding, indicating that site B is the primary proteoglycan-binding site of LDL. Although site B was essential for normal receptor-binding and proteoglycan-binding activities, these activities could be separated in recombinant LDL containing single-point mutation. Recombinant LDL with a K3363E mutation, in which a glutamic acid had been inserted into the basic cluster RKR in site B, had normal receptor binding but interacted defectively with proteoglycans; in contrast, another mutant LDL, R3500Q, displayed defective receptor binding but interacted normally with proteoglycans. LDL with normal receptor-binding activity but with severely impaired proteoglycan binding will be a unique resource for analyzing the importance of LDL- proteoglycan interaction in atherogenesis. If the subendothelial retention of LDL by proteoglycans is the initial event in early atherosclerosis, then LDL with defective proteoglycan binding may have little or no atherogenic potential.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=508856Documentos Relacionados
- Lipoprotein clearance mechanisms in LDL receptor-deficient "Apo-B48-only" and "Apo-B100-only" mice.
- Biological Activity of Ectodysplasin A Is Conditioned by Its Collagen and Heparan Sulfate Proteoglycan-binding Domains*
- Lactoferrin Inhibits the Lipopolysaccharide-Induced Expression and Proteoglycan-Binding Ability of Interleukin-8 in Human Endothelial Cells
- Identification of the low density lipoprotein receptor-binding site in apolipoprotein B100 and the modulation of its binding activity by the carboxyl terminus in familial defective apo-B100.
- Specific in vitro transcription of conalbumin gene is drastically decreased by single-point mutation in T-A-T-A box homology sequence.