Biochemical signal transmitted by Fc gamma receptors: phospholipase A2 activity of Fc gamma 2b receptor of murine macrophage cell line P388D1.
Biochemical signal transmitted by Fc gamma receptors: phospholipase A2 activity of Fc gamma 2b receptor of murine macrophage cell line P388D1.
复制标题
Fc γ 受体传递的生化信号：鼠巨噬细胞系 P388D1 的 Fc γ 2b 受体的磷脂酶 A2 活性。
DOI：
10.1073/pnas.79.2.591
复制
发表时间：
1982
影响因子：
11.1
通讯作者：
T. Nitta
中科院分区：
文献类型：
--
作者：
T. Suzuki;T. Saito‐Taki;R. Sadasivan;T. Nitta
将P388D1巨噬细胞的洗洁精裂解液在两种不同的培养基上进行亲和层析，分别是与热聚集的人IgG （IgG-Sepharose）偶联的Sepharose和与磷脂酰胆碱类似物rac1 -（9-羧基）壬基-2- 16烷基甘油-3-磷酸胆碱（PC-Sepharose）偶联的Sepharose。通过Sephadex G-100凝胶过滤和6 M尿素等电聚焦进一步纯化IgG和磷脂酰胆碱结合蛋白。分离的igg结合蛋白特异性结合IgG2a，但不结合IgG2b，而分离的磷脂酰胆碱结合蛋白特异性结合IgG2b，但不结合IgG2a。磷脂酰胆碱结合蛋白具有典型的磷脂酶A2活性（磷脂酰2-酰基水解酶，EC 3.1.1.4），在pH 9.5时最大（10 μ mol/min / mg蛋白），依赖于Ca2+，并且特异性地从磷脂酰胆碱的甘油主链的C-2位置裂解脂肪酸。将磷脂酰胆碱结合蛋白与热聚集的小鼠IgG2b预孵育后，酶活性增加了4倍，但与IgG2a不孵育。另一方面，igg结合蛋白缺乏任何可检测到的磷脂酶A2活性。因此，Fc γ 2b受体在P388D1巨噬细胞系中的功能意义在于与Fc γ 2b片段特异性结合后在细胞表面产生磷脂酶A2活性。
The detergent lysate of the P388D1 macrophage cell line was subjected to affinity chromatography on two different media, Sepharose coupled to heat-aggregated human IgG (IgG-Sepharose) and Sepharose coupled to the phosphatidylcholine analog rac-1-(9-carboxyl)nonyl-2-hexadecylglycero-3-phosphocholine (PC-Sepharose). Both IgG- and phosphatidylcholine-binding proteins were further purified by Sephadex G-100 gel filtration and isoelectric focusing in the presence of 6 M urea. The isolated IgG-binding proteins specifically bound to IgG2a, but not to IgG2b, whereas the isolated phosphatidylcholine-binding proteins specifically bound to IgG2b but not to IgG2a. Phosphatidylcholine-binding proteins possessed a typical phospholipase A2 activity (phosphatide 2-acylhydrolase, EC 3.1.1.4), which was maximal (10 mumol/min per mg of protein) at pH 9.5, depended on Ca2+, and was specific for cleavage of fatty acid from the C-2 position of the glycerol backbone of phosphatidylcholine. The noted enzymatic activity was augmented 4-fold by preincubating phosphatidylcholine-binding proteins with heat-aggregated murine IgG2b but not with IgG2a. IgG-binding proteins, on the other hand, are devoid of any detectable phospholipase A2 activity. Thus, the functional significance of Fc gamma 2b receptor of P388D1 macrophage cell line would be the generation of phospholipase A2 activity at the cell surface upon specific binding to Fc gamma 2b fragment.