Young J D, Unkeless J C, Young T M, Mauro A, Cohn Z A
Nature. 1983;306(5939):186-9. doi: 10.1038/306186a0.
The interaction of ligands with the mouse macrophage Fc receptor which binds IgG2b and IgG1 immune complexes (FcR gamma 2b/gamma 1) triggers phagocytosis and secretion of various mediators of inflammation. FcR gamma 2b/gamma 1 has been purified using a monoclonal anti-FcR antibody, 2.4G2, and seems to be an integral membrane glycoprotein of molecular weight (Mr) 47,000-60,000 (ref. 6). Monoclonal antibody 2.4G2 is suitable as a tool for functional studies of FcR because it binds to a functional site of the receptor and induces cellular responses that are normally associated with the occupied receptor. We reported previously that binding of ligands to the macrophage FcR resulted in Na+/K+ ion fluxes through the plasma membrane, and that similar ion fluxes were observed in proteoliposomes containing reconstituted FcR. We have now incorporated FcR into planar lipid bilayers and report here that FcR gamma 2b/gamma 1 forms ligand-dependent cation-selective ion channels, with a conductance of 60 pS in 1 M KCl and an average open channel lifetime of 250 ms. The conductance decays to baseline levels within a few minutes. These results suggest a receptor-ionophore model for the signalling of phagocytosis and inflammatory responses.
配体与小鼠巨噬细胞Fc受体（可结合IgG2b和IgG1免疫复合物，即FcRγ2b/γ1）的相互作用会引发吞噬作用以及多种炎症介质的分泌。FcRγ2b/γ1已使用单克隆抗FcR抗体2.4G2进行了纯化，它似乎是一种分子量（Mr）为47,000 - 60,000的整合膜糖蛋白（参考文献6）。单克隆抗体2.4G2适合作为FcR功能研究的工具，因为它能与受体的功能位点结合，并诱导出通常与被占据受体相关的细胞反应。我们之前报道过，配体与巨噬细胞FcR的结合会导致Na⁺/K⁺离子通过质膜流动，并且在含有重组FcR的蛋白脂质体中也观察到了类似的离子流动。我们现在已将FcR整合到平面脂质双分子层中，并在此报告FcRγ2b/γ1形成了配体依赖性阳离子选择性离子通道，在1 M KCl中电导为60 pS，平均开放通道寿命为250毫秒。电导在几分钟内衰减至基线水平。这些结果提示了一种用于吞噬作用和炎症反应信号传导的受体 - 离子载体模型。
