Abstract：
One of the first cellular locations of the calreticulin (CRT) chaperone in eukaryotic cells, apart from its obvious localization in the endoplasmic reticulum (ER), was the cell nucleus (Opas et al. 1991). The presence of CRT has been detected inside the nucleus and in the nuclear envelope of animal and plant cells, and a putative nuclear localization signal (NLS) in the CRT amino acid sequence has been mapped in several animal and plant species. Over the last 30 years, other localization sites of this protein outside the ER and cell nucleus have also been discovered, suggesting that CRT is a multifunctional Ca2+-binding protein widely found in various cell types. In our previous studies focusing on plant developmental biology, we have demonstrated the presence of CRT inside and outside the ER in highly specialized plant cells, as well as the possibility of CRT localization in the cell nucleus. In this paper, we present a detailed analysis of immunocytochemical localization of CRT inside nuclei of the pistil transmission tract somatic cells before and after pollination. We show a similar pattern of the nuclear CRT localization in relation to exchangeable Ca2+ for two selected species of angiosperms, dicotyledonous Petunia and monocot Haemanthus, that differ in anatomical structure of the pistil and discuss the potential role of CRT in the cell nucleus.
摘要：
真核细胞中钙网蛋白（CRT）伴侣的第一个细胞位置之一，除了其在内质网（ER）中的明显定位外，是细胞核(Opas等人。1991).在细胞核内和动物和植物细胞的核膜中检测到CRT的存在，CRT氨基酸序列中的推定核定位信号（NLS）已在几种动植物物种中定位。在过去的30年里,还发现了该蛋白质在ER和细胞核外的其他定位位点，表明CRT是广泛存在于各种细胞类型中的多功能Ca2+结合蛋白。在我们以前的研究集中在植物发育生物学，我们已经证明了CRT在高度专业化的植物细胞内和外的存在，以及CRT在细胞核中定位的可能性。在本文中,我们提供了一个详细的分析，在授粉前后，CRT在雌蕊传递道体细胞核内的免疫细胞化学定位。我们显示了与两个选定的被子植物物种的可交换Ca2相关的核CRT定位的相似模式，双子叶矮牵牛和单子叶，雌蕊的解剖结构不同，并讨论CRT在细胞核中的潜在作用。
