Lipopolysaccharide binding protein and soluble CD14 catalyze exchange of phospholipids
| Autor: | E Hailman, B Yu, S D Wright |
|---|---|
| Rok vydání: | 1997 |
| Předmět: |
Lipopolysaccharides
Lipid Bilayers Phospholipid Lipopolysaccharide Receptors Phosphatidylinositols chemistry.chemical_compound Salmonella Phosphatidylcholine Humans Phosphatidylinositol Binding site Lipid bilayer Phospholipids Phosphatidylethanolamine Membrane Glycoproteins biology Phosphatidylethanolamines Biological Transport General Medicine Blood Proteins Blood proteins Recombinant Proteins nervous system diseases Spectrometry Fluorescence chemistry Biochemistry Models Chemical Solubility biology.protein Phosphatidylcholines lipids (amino acids peptides and proteins) Carrier Proteins Lipoproteins HDL Lipopolysaccharide binding protein Acute-Phase Proteins Research Article |
| Zdroj: | The Journal of clinical investigation. 99(2) |
| ISSN: | 0021-9738 |
| Popis: | Lipopolysaccharide binding protein (LBP) is a plasma protein known to facilitate the diffusion of bacterial LPS (endotoxin). LBP catalyzes movement of LPS monomers from LPS aggregates to HDL particles, to phospholipid bilayers, and to a binding site on a second plasma protein, soluble CD14 (sCD14). sCD14 can hasten transfer by receiving an LPS monomer from an LPS aggregate, and then surrendering it to an HDL particle, thus acting as a soluble "shuttle" for an insoluble lipid. Here we show that LBP and sCD14 shuttle not only LPS, but also phospholipids. Phosphatidylinositol (PI), phosphatidylcholine, and a fluorescently labeled derivative of phosphatidylethanolamine (R-PE) are each transferred by LBP from membranes to HDL particles. The transfer could be observed using recombinant LBP and sCD14 or whole human plasma, and the plasma-mediated transfer of PI could be blocked by anti-LBP and partially inhibited by anti-CD14. sCD14 appears to act as a soluble shuttle for phospholipids since direct binding of PI and R-PE to sCD14 was observed and because addition of sCD14 accelerated transfer of these lipids. These studies define a new function for LBP and sCD14 and describe a novel mechanism for the transfer of phospholipids in blood. In further studies, we show evidence suggesting that LBP transfers LPS and phospholipids by reciprocal exchange: LBP-catalyzed binding of R-PE to LPS x sCD14 complexes was accompanied by the exit of LPS from sCD14, and LBP-catalyzed binding of R-PE to sCD14 was accelerated by prior binding of LPS to sCD14. Binding of one lipid is thus functionally coupled with the release of a second. These results suggest that LBP acts as a lipid exchange protein. |
| Databáze: | OpenAIRE |
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