Chock S P, Schmauder-Chock E A, Cordella-Miele E, Miele L, Mukherjee A B
Department of Biochemistry and Molecular Biology, Howard University School of Medicine, Washington, DC 20059.
Biochem J. 1994 Jun 15;300 ( Pt 3)(Pt 3):619-22. doi: 10.1042/bj3000619.
A heat-resistant phospholipase A2 has been detected in the secretory granules of the mast cell [Chock, Rhee, Tang and Schmauder-Chock (1991) Eur. J. Biochem. 195, 707-713]. By using ultrastructural immunocytochemical techniques, we have now localized this enzyme to the matrix of the secretory granule. Like the cyclo-oxygenase [Schmauder-Chock and Chock (1989) J. Histochem. Cytochem. 37, 1319-1328], this enzyme also adheres tightly to the ribbon-like granule matrix components. The results from Western-blot analysis suggest that it has a molecular mass of about 14 kDa. The localization of the phospholipase A2, the presence of a phospholipid store with millimolar concentrations of calcium and the localization of the enzymes of the arachidonic acid cascade make the secretory granule a natural site for lipid-mediator synthesis. The packaging of phospholipase A2, together with its substrate and the components of the arachidonic acid cascade, in the secretory granule represents a physical arrangement by which the initiation of the cascade and the release of mediators can be directly linked to the stimulation of cell-surface receptors.
已在肥大细胞的分泌颗粒中检测到一种耐热磷脂酶A2[乔克、李、唐和施毛德-乔克（1991年）《欧洲生物化学杂志》195卷，707 - 713页]。通过使用超微结构免疫细胞化学技术，我们现已将这种酶定位到分泌颗粒的基质中。与环氧化酶[施毛德-乔克和乔克（1989年）《组织化学与细胞化学杂志》37卷，1319 - 1328页]一样，这种酶也紧密附着于带状颗粒基质成分。蛋白质印迹分析结果表明其分子量约为14 kDa。磷脂酶A2的定位、存在毫摩尔浓度钙的磷脂储存以及花生四烯酸级联反应中各种酶的定位，使得分泌颗粒成为脂质介质合成的天然场所。磷脂酶A2与其底物以及花生四烯酸级联反应的成分一起包装在分泌颗粒中，这是一种物理排列，通过这种排列，级联反应的启动和介质的释放可以直接与细胞表面受体的刺激联系起来。
