Targeting of OSBP-related protein 3 (ORP3) to endoplasmic reticulum and plasma membrane is controlled by multiple determinants
Targeting of OSBP-related protein 3 (ORP3) to endoplasmic reticulum and plasma membrane is controlled by multiple determinants
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DOI：
10.1016/j.yexcr.2005.08.003
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发表时间：
2005-11-01
影响因子：
3.7
通讯作者：
Olkkonen, VM
中科院分区：
文献类型：
--
作者：
Lehto, M;Hynynen, R;Olkkonen, VM
使用一系列截断和点突变构建体研究了氧甾醇结合蛋白（OSBP）相关蛋白3 （ORP3）的细胞内靶向决定因素。OPP3的pleckstrin同源（PH）结构域结合磷酸肌醇-3激酶（PI3K）产物PI(3,4)P-2和PI(3,4,5)P-3。一个功能性的PH结构域和侧翼序列对于ORP3的质膜靶向至关重要。靶向ORP3的内质网（ER）受FFAT基序（EFFDAxE）调控，该基序介导与vamp相关蛋白(VAP)-A的相互作用。FFAT基序的靶向功能优于PH结构域。此外，外显子10/11区域调节ORP3与内质网和核膜的相互作用。对ORP3:OSBP嵌合蛋白的分析表明，OSBP c端结构域的配体结合可诱导变构变化，从而激活ORP3的n端靶向模块。值得注意的是，ORP3和VAP-A的过表达诱导了堆叠的内质网膜结构，也称为有组织的光滑内质网（OSER）。此外，脂质饥饿促进依赖于ORP3蛋白的扩张外周内质网（DPER）结构的形成。基于目前的数据，我们引入了ORP3在膜靶向蛋白中功能域相互关系的模型。(c) 2005爱思唯尔公司版权所有。
The intracellular targeting determinants of oxysterol binding protein (OSBP)-related protein 3 (ORP3) were studied using a series of truncated and point mutated constructs. The pleckstrin homology (PH) domain of OPP3 binds the phosphoinositide-3-kinase (PI3K) products, PI(3,4)P-2 and PI(3,4,5)P-3. A functional PH domain and flanking sequences are crucial for the plasma membrane (PM) targeting of ORP3. The endoplasmic reticulum (ER) targeting of ORP3 is regulated the by a FFAT motif (EFFDAxE), which mediates interaction with VAMP-associated protein (VAP)-A. The targeting function of the FFAT motif dominates over that of the PH domain. In addition, the exon 10/11 region modulates interaction of ORP3 with the ER and the nuclear membrane. Analysis of a chimeric ORP3:OSBP protein suggests that ligand binding by the C-terminal domain of OSBP induces allosteric changes that activate the N-terminal targeting modules of ORP3. Notably, over-expression of ORP3 together with VAP-A induces stacked ER membrane structures also known as organized smooth ER (OSER). Moreover, lipid starvation promotes formation of dilated peripheral ER (DPER) structures dependent on the ORP3 protein. Based on the present data, we introduce a model for the inter-relationships of the functional domains of ORP3 in the membrane targeting of the protein. (c) 2005 Elsevier Inc. All rights reserved.