Zarewych D M, Kindzelskii A L, Todd R F, Petty H R
Department of Biological Sciences, Wayne State University, Detroit, MI 48202, USA.
J Immunol. 1996 Jan 15;156(2):430-3.
CD14, a glycosylphosphatidyl inositol (GPI)-linked membrane protein, is a key membrane binding site for LPS (endotoxin). Although CD14 lacks transmembrane and cytoplasmic sequences, it activates CR3-mediated leukocyte adhesion and cytokine release. Since CR3 has been shown to interact with other GPI-linked membrane proteins, we tested the hypothesis that CD14 can physically associate with CR3. Using qualitative and quantitative resonance energy transfer microscopy, we show that LPS in the presence of serum or LPS binding protein triggers formation of CD14-CR3 complexes. Kinetic studies show that CD14-CR3 complexes dissociate as neutrophils attach to substrates. We speculate that LPS-charged CD14 enhances CR3-mediated adhesion by directly binding to CR3.
CD14是一种糖基磷脂酰肌醇（GPI）连接的膜蛋白，是脂多糖（内毒素）的关键膜结合位点。尽管CD14缺乏跨膜和细胞质序列，但它可激活CR3介导的白细胞黏附和细胞因子释放。由于已证明CR3可与其他GPI连接的膜蛋白相互作用，我们检验了CD14可与CR3发生物理缔合的假说。使用定性和定量共振能量转移显微镜，我们发现血清或脂多糖结合蛋白存在时的脂多糖会触发CD14 - CR3复合物的形成。动力学研究表明，当中性粒细胞附着于底物时，CD14 - CR3复合物会解离。我们推测，带脂多糖电荷的CD14通过直接结合CR3来增强CR3介导的黏附。
