Hong S L, Deykin D
J Biol Chem. 1979 Nov 25;254(22):11463-6.
Methylcholanthrene-transformed mouse fibroblasts synthesize prostaglandins in response to bradykinin, thrombin, serum, and the ionophore A23187. These agents activate phospholipases, thereby releasing fatty acids from phospholipids. To examine the phospholipid specificity of the phospholipases activated by bradykinin, thrombin, serum, and A23187, cells were labeled with [14C]arachidonic acid and stimulated with these agents in the presence of delipidated bovine serum albumin. Phospholipid classes were resolved by two-dimensional chromatography on silica gel-coated paper. Only phosphatidylinositol and phosphatidylcholine lost radioactivity upon stimulation. To characterize the fatty acid specificity of the phospholipases, cells were incubated with 14C-labeled stearic, oleic, linoleic, eicosatrienoic, or arachidonic acid and then exposed to the stimuli. Bradykinin, thrombin, and serum caused specific release of radioactivity into the medium only from cells labeled with arachidonic acid or eicosatrienoic acid, whereas A23187 caused release from cells labeled with any one of the five fatty acids. We conclude that bradykinin, thrombin, and serum activate phospholipases that specifically hydrolyze arachidonyl and eicosatrienoyl phosphatidylinositol and phosphatidylcholine, whereas A23187 is less specific activator of phospholipases.
甲基胆蒽转化的小鼠成纤维细胞可响应缓激肽、凝血酶、血清及离子载体A23187合成前列腺素。这些物质激活磷脂酶，从而从磷脂中释放脂肪酸。为检测缓激肽、凝血酶、血清及A23187激活的磷脂酶的磷脂特异性，细胞用[14C]花生四烯酸标记，并在脱脂牛血清白蛋白存在的情况下用这些物质刺激。磷脂类通过在硅胶涂层纸上的二维色谱法分离。刺激后只有磷脂酰肌醇和磷脂酰胆碱失去放射性。为表征磷脂酶的脂肪酸特异性，细胞与14C标记的硬脂酸、油酸、亚油酸、二十碳三烯酸或花生四烯酸孵育，然后暴露于刺激物。缓激肽、凝血酶和血清仅导致放射性从用花生四烯酸或二十碳三烯酸标记的细胞中特异性释放到培养基中，而A23187导致放射性从用五种脂肪酸中的任何一种标记的细胞中释放。我们得出结论，缓激肽、凝血酶和血清激活特异性水解花生四烯酰基和二十碳三烯酰基磷脂酰肌醇及磷脂酰胆碱的磷脂酶，而A23187是磷脂酶的特异性较低的激活剂。
