Identification of the junctional plaque protein plakophilin 3 in cytoplasmic particles containing RNA-binding proteins and the recruitment of plakophilins 1 and 3 to stress granules
Identification of the junctional plaque protein plakophilin 3 in cytoplasmic particles containing RNA-binding proteins and the recruitment of plakophilins 1 and 3 to stress granules
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DOI：
10.1091/mbc.e05-08-0708
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发表时间：
2006-03-01
影响因子：
3.3
通讯作者：
Franke, WW
中科院分区：
文献类型：
--
作者：
Hofmann, I;Casella, M;Franke, WW
最近对细胞间连接的细胞质斑块蛋白的亚细胞分布的研究表明，一些这样的蛋白质也可以发生在细胞质和核质中。这种发生在不同的，遥远的位置表明，一些斑块蛋白质发挥作用，在细胞质和核的过程中，除了他们参与细胞-细胞粘附相互作用。Plakophilin（PKP）3是蛋白质的臂重复家族的成员，存在于多种细胞类型中，既作为桥粒斑块中的结构组分，又分散在细胞质颗粒中。在使用PKP3特异性抗体的免疫选择实验中，我们通过质谱分析鉴定了以下RNA结合蛋白：Poly（A）结合蛋白（PABPC 1）、脆性X相关蛋白（FXR1）和ras-GAP-SH3结合蛋白（G3BP）。蔗糖梯度离心后，RNA结合蛋白共分布在25 - 35 S和45 - 55 S的PKP3组分中。当细胞暴露于环境压力（例如，热休克或氧化应激）蛋白FXR1、G3BP和PABPC1与PKP3或PKP1一起在已知积累停滞的翻译起始复合物的"应激颗粒"中发现。此外，在PKP3颗粒中还检测到蛋白eIF-4E和核糖体蛋白S6。我们的研究结果表明，细胞质PKP3是组成性相关的RNA结合蛋白，并表示参与翻译和RNA代谢的过程。
Recent studies on the subcellular distribution of cytoplasmic plaque proteins of intercellular junctions have revealed that a number of such proteins can also occur in the cyto- and the nucleoplasm. This occurrence in different, and distant locations suggest that some plaque proteins play roles in cytoplasmic and nuclear processes in addition to their involvement in cell-cell adhesive interactions. Plakophilin (PKP) 3, a member of the arm-repeat family of proteins, occurs, in a diversity of cell types, both as an architectural component in plaques of desmosomes and dispersed in cytoplasmic particles. In immuno-selection experiments using PKP3-specific antibodies, we have identified by mass spectrometric analysis the following RNA-binding proteins: Poly (A) binding protein (PABPC1), fragile-X-related protein (FXR1), and ras-GAP-SH3-binding protein (G3BP). Moreover, the RNA-binding proteins codistributed after sucrose gradient centrifugation in PKP3-containing fractions corresponding to 25-35 S and 45-55 S. When cells are exposed to environmental stress (e.g., heat shock or oxidative stress) proteins FXR1, G3BP, and PABPC1 are found, together with PKP3 or PKP1, in "stress granules" known to accumulate stalled translation initiation complexes. Moreover, the protein eIF-4E and the ribosomal protein S6 are also detected in PKP3 particles. Our results show that cytoplasmic PKP3 is constitutively associated with RNA-binding proteins and indicate an involvement in processes of translation and RNA metabolism.