拟南芥富含亮氨酸重复序列类受体激酶AtLRR78A的定位及其分选序列研究

The localization and trafficking mechanism of AtLRR78A,a leucine-rich repeat receptor-like kinase (LRR-RLK) in Arabidopsis

富含亮氨酸重复类受体蛋白激酶(LRR-RLKs)是类受体蛋白激酶家族中已知的最大的亚家族。目前的研究表明:LRR-RLKs包含一个胞外的LRR结构域和一个胞内丝氨酸/苏氨酸(Ser/Thr)激酶结构域,能够充当胞外信号的受体从而参与各种环境及发育信号的感知和传递。虽然所有的相关报道都显示LRR-RLKs定位于细胞质膜,但LRR-RLK在胞内分拣运输的机制仍不是很清楚。在本研究中,我们分析了一种典型的LRR-RLK(AtLRR78A),它进行反式高尔基网络(TGN)、液泡前体(PVC)和液泡(vacuolar)的分拣运输。At LRR78A的N端共960 aa(NT960)在质膜的形成过程中扮演着重要的角色,但其C端共1 056 aa(CT1056)不是质膜定位所必需的。同时我们发现AtLRR78A的NT960可以引导AtVSR2从PVC转位到液泡膜(TP),并且仅AtVSR2的CT1056就能使定位在质膜的AtLRR78A分拣运输到PVC和液泡膜。

Leucine-rich repeat receptor-like kinases （LRR-RLKs）, consisted of an extracellular LRR and intra- cellular Ser/Thr kinase domain, act as extracellular signal receptors and participate in perception and transmis- sion of various environmental and developmental signals. So far, almost all the reports show that LRR-RLKs are localized at the plasma membrane, but the detail mechanisms of LRR-RLK protein trafficking are still un- clear. Here, we analyzed a kind of typical LRR-RLK protein, which localized at plasma membrane and in- volved in trans-Golgi network （TGN）, pre-vacuolar compartment （PVC） and vacuolar traffickings. N-terminal （NT） of LRR-RLK played an important role in formation of plasma membrane localization, and C-terminal （CT） was not required for plasma membrane localization. At the same time, NT could guide AtVSR2 protein translocation from PVC to tonoplast, and only CT of AtVSR2 could guide LRR protein from PM to PVC and tonoplast pathway in this study.