Dynamique des Interactions membranaires Normales et Pathologiques, UMR CNRS, Université de Montpellier, Montpellier, France.
Int J Parasitol. 2009 Feb;39(3):299-306. doi: 10.1016/j.ijpara.2008.07.011. Epub 2008 Sep 20.
The intracellular protozoan parasite Toxoplasma gondii develops within the parasitophorous vacuole (PV), an intracellular niche in which it secretes proteins from secretory organelles named dense granules and rhoptries. Here, we describe a new dense granule protein that should now be referred to as GRA12, and that displays no homology with other proteins. Immunofluorescence and immuno-electron microscopy showed that GRA12 behaves similarly to both GRA2 and GRA6. It is secreted into the PV from the anterior pole of the parasite soon after the beginning of invasion, transits to the posterior invaginated pocket of the parasite where a membranous tubulovesicular network is first assembled, and finally resides throughout the vacuolar space, associated with the mature membranous nanotubular network. GRA12 fails to localise at the parasite posterior end in the absence of GRA2. Within the vacuolar space, like the other GRA proteins, GRA12 exists in both a soluble and a membrane-associated form. Using affinity chromatography experiments, we showed that in both the parasite and the PV soluble fractions, GRA12 is purified with the complex of GRA proteins associated with a tagged version of GRA2 and that this association is lost in the PV membranous fraction.
细胞内原生动物寄生虫刚地弓形虫在吞噬小泡（PV）内发育，这是一种细胞内小生境，它从称为致密颗粒和棒状体的分泌细胞器中分泌蛋白质。在这里，我们描述了一种新的致密颗粒蛋白，现在应该称为 GRA12，它与其他蛋白没有同源性。免疫荧光和免疫电子显微镜显示，GRA12 的行为与 GRA2 和 GRA6 相似。它在寄生虫入侵开始后不久从前极分泌到 PV 中，转运到寄生虫后内陷的口袋中，在那里首先组装膜管状泡状网络，最后存在于整个空泡空间中，与成熟的膜状纳米管状网络相关。如果没有 GRA2，GRA12 就无法定位于寄生虫后端。在空泡空间中，与其他 GRA 蛋白一样，GRA12 以可溶性和膜相关形式存在。通过亲和层析实验，我们表明在寄生虫和 PV 可溶性部分中，GRA12 与与标记的 GRA2 相关联的 GRA 蛋白复合物一起被纯化，并且这种关联在 PV 膜部分中丢失。
