Lipopolysaccharide (LPS)-binding protein accelerates the binding of LPS to CD14.
Lipopolysaccharide (LPS)-binding protein accelerates the binding of LPS to CD14.
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DOI：
10.1084/jem.179.1.269
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发表时间：
1994-01-01
期刊：
影响因子：
--
通讯作者：
Wright SD
中科院分区：
文献类型：
--
作者：
Hailman E;Lichenstein HS;Wurfel MM;Miller DS;Johnson DA;Kelley M;Busse LA;Zukowski MM;Wright SD
CD 14是一种55 kD蛋白质，作为单核细胞、巨噬细胞和多形核白细胞表面的糖基磷脂酰肌醇（GPI）锚定蛋白，以及血液中的可溶性蛋白。两种形式的CD 14都参与细胞对细菌脂多糖（LPS）的血清依赖性应答。虽然CD 14被描述为LPS与LPS结合蛋白（LBP）复合物的受体，但没有直接证据表明是否形成了LPS、LBP和CD 14的三元复合物，或者CD 14是否直接结合LPS。使用非变性聚丙烯酰胺凝胶电泳（native PAGE），我们表明，重组可溶性CD 14（rsCD 14）结合LPS的LBP或其他蛋白的情况下。LPS与CD 14的结合是稳定的并且具有低化学计量（每个rsCD 14一个或两个LPS分子）。重组LBP（rLBP）不与rsCD 14和LPS形成可检测的三元复合物，但它确实加速LPS与rsCD 14的结合。rLBP促进LPS与rsCD 14在亚化学计量浓度下的相互作用，表明LBP作为脂质转移蛋白具有催化作用。在LBP或其他血清蛋白不存在的情况下形成的LPS和rsCD 14的复合物强烈刺激PMN上的整合素功能和内皮细胞上的E-选择素的表达，表明LBP对于CD 14依赖性细胞刺激不是必需的。这些结果表明，CD 14作为LPS的可溶性和细胞表面受体，并且LBP可能主要起加速LPS与CD 14结合的作用。
CD14 is a 55-kD protein found as a glycosylphosphatidylinositol (GPI)- anchored protein on the surface of monocytes, macrophages, and polymorphonuclear leukocytes, and as a soluble protein in the blood. Both forms of CD14 participate in the serum-dependent responses of cells to bacterial lipopolysaccharide (LPS). While CD14 has been described as a receptor for complexes of LPS with LPS-binding protein (LBP), there has been no direct evidence showing whether a ternary complex of LPS, LBP, and CD14 is formed, or whether CD14 binds LPS directly. Using nondenaturing polyacrylamide gel electrophoresis (native PAGE), we show that recombinant soluble CD14 (rsCD14) binds LPS in the absence of LBP or other proteins. Binding of LPS to CD14 is stable and of low stoichiometry (one or two molecules of LPS per rsCD14). Recombinant LBP (rLBP) does not form detectable ternary complexes with rsCD14 and LPS, but it does accelerate the binding of LPS to rsCD14. rLBP facilitates the interaction of LPS with rsCD14 at substoichiometric concentrations, suggesting that LBP functions catalytically, as a lipid transfer protein. Complexes of LPS and rsCD14 formed in the absence of LBP or other serum proteins strongly stimulate integrin function on PMN and expression of E-selectin on endothelial cells, demonstrating that LBP is not necessary for CD14-dependent stimulation of cells. These results suggest that CD14 acts as a soluble and cell surface receptor for LPS, and that LBP may function primarily to accelerate the binding of LPS to CD14.