植物EXO70基因家族的研究进展

胞吐是存在于所有真核生物的一种极其重要的细胞活动，直接参与了激素和神经信号的分泌、细胞生长、细胞极性的建立，细胞分裂和细胞壁的形成等多项生理过程。在胞吐过程中，高尔基后转运膜泡与靶膜的识别是由进化上高度保守的胞泌复合体（exocyst）介导的。该复合体由8个蛋白亚基构成，其中EXO70是组成胞泌复合体功能的关键亚基，可与小G蛋白和膜脂互作，参与复合体在靶膜组装。目前，对植物胞泌复合体功能的了解非常有限，已有证据显示其广泛参与了细胞生长，细胞壁形成、细胞分裂等多种生物学过程。与酵母和动物相比，植物胞泌复合体的一个显著特征是：EXO70在高等植物基因组中存在多个同源基因，其具体生物学功能尚不清楚。本文综述胞泌复合体的研究进展，重点讨论植物EXO70的多基因家族，推测不同的EXO70可能参与了组织细胞或运载底物特异的膜泡转运过程。

Research Advance of the EXO70 Gene Family in Plants

Exocytosis is fundamental in eukaryotic organisms for a wide-range of cell biological processes and directly participates in hormones and neurotransmitters secretion, cell growth, cell polarity establishment, cytokinesis and cell wall formation. During exocytosis, the specific recognization between post-Golgi vesicles and the target membranes is mediated by an evolutionary conserved multiprotein complex named the exocyst. The exocyst is compromised of 8 subunits. Of these, EXO70 interacts with small GTPases and phosphatidylinositol 4,5-bisphosphate PIP2] on the target membrane, and plays a key role in exocyst assymbly at target membrane. Now, knowledge about the function of the exocyst is still little. But it is demonstrated that the exocyst participates in various biological processes such as cell growth, cell wall formation and cytokinesis. In contrast to a single gene in yeast and most animal genomes, the number of EXO70 encoding for EXO70 homologs increased greatly in plant genomes with their function much unknown. In this review, we summarize research progress on EXO70 and foucus on the land plant EXO70 gene family. We proposed that individual EXO70 members in plants may regulate cell typeor cargo-specific exocytosis.