Endoplasmic reticulum membrane receptors of the GET pathway are conserved throughout eukaryotes.
Endoplasmic reticulum membrane receptors of the GET pathway are conserved throughout eukaryotes.
复制标题
DOI：
10.1073/pnas.2017636118
复制
发表时间：
2021-01-05
影响因子：
11.1
通讯作者：
Grefen C
中科院分区：
文献类型：
--
作者：
Asseck LY;Mehlhorn DG;Monroy JR;Ricardi MM;Breuninger H;Wallmeroth N;Berendzen KW;Nowrousian M;Xing S;Schwappach B;Bayer M;Grefen C
GET途径是酵母和哺乳动物内质网（ER）中尾锚定（TA）膜蛋白插入所必需的。除了膜插入所需的两个内质网膜受体中的一个外，在高等植物中也发现了一些同源基因。Get2/CAML是该途径的细胞质伴侣对接并释放TA蛋白货物所必需的。在这里，我们报告通过相互作用筛选鉴定难以捉摸的植物GET途径受体在拟南芥。该候选物允许在高等植物中进一步检测Get2/CAML同源物，揭示跨界结构特征的保护和功能。此外，我们的研究结果表明，这些特征，而不是序列保守，决定了候选通路中的功能。II型尾锚定（TA）膜蛋白参与多种细胞过程，包括蛋白质易位、囊泡运输和细胞凋亡。它们的特点是具有单一的c端跨膜结构域，通过TA蛋白的引导进入途径介导翻译后靶向和插入内质网（ER）。GET系统最初在哺乳动物和酵母中被描述，但最近被证明在其他真核生物（如高等植物）中部分保守。新合成的TA蛋白被预靶向复合物和atp酶从细胞质中屏蔽，atp酶将蛋白质递送到内质网，在内质网中，膜受体（Get1/WRB和Get2/CAML）促进插入。在模式植物拟南芥中，该通路的大部分成分都是通过硅序列比较确定的，然而，辅助受体Get2/CAML的功能同源物仍然是未知的。我们采用免疫沉淀-质谱分析检测AtGET1的体内相互作用物，并鉴定出一个功能未知的膜蛋白，其序列同源性低，但结构同源性高，与酵母Get2和哺乳动物CAML都具有同源性。该蛋白定位于内质网膜，与AtGET1共表达，并结合拟南芥GET途径组分。虽然功能缺失系表现出其他Atget系的根毛发育不良表型，但其异源表达与辅助受体AtGET1一起挽救了Δget1get2酵母的生长缺陷。胞质内带正电的N端异位表达足以在体外阻断TA蛋白的插入。我们的研究结果共同证实，我们已经在拟南芥中发现了一个植物特异性的GET2，其序列允许跨界途径保守分析。
The GET pathway is required for the insertion of tail-anchored (TA) membrane proteins in the endoplasmic reticulum (ER) of yeast and mammals. Some orthologous genes had also been identified in higher plants with the exception of one of the two ER membrane receptors required for membrane insertion. Get2/CAML is required for the pathway’s cytosolic chaperone to dock and release its TA protein cargo. Here we report the identification of the elusive plant GET pathway receptor through an interaction screen in Arabidopsis. The candidate allows detection of further Get2/CAML orthologs in higher plants, revealing conservation and function of structural features across kingdoms. Additionally, our results demonstrate that these features, rather than sequence conservation, determine functionality of the candidate within the pathway. Type II tail-anchored (TA) membrane proteins are involved in diverse cellular processes, including protein translocation, vesicle trafficking, and apoptosis. They are characterized by a single C-terminal transmembrane domain that mediates posttranslational targeting and insertion into the endoplasmic reticulum (ER) via the Guided-Entry of TA proteins (GET) pathway. The GET system was originally described in mammals and yeast but was recently shown to be partially conserved in other eukaryotes, such as higher plants. A newly synthesized TA protein is shielded from the cytosol by a pretargeting complex and an ATPase that delivers the protein to the ER, where membrane receptors (Get1/WRB and Get2/CAML) facilitate insertion. In the model plant Arabidopsis thaliana, most components of the pathway were identified through in silico sequence comparison, however, a functional homolog of the coreceptor Get2/CAML remained elusive. We performed immunoprecipitation-mass spectrometry analysis to detect in vivo interactors of AtGET1 and identified a membrane protein of unknown function with low sequence homology but high structural homology to both yeast Get2 and mammalian CAML. The protein localizes to the ER membrane, coexpresses with AtGET1, and binds to Arabidopsis GET pathway components. While loss-of-function lines phenocopy the stunted root hair phenotype of other Atget lines, its heterologous expression together with the coreceptor AtGET1 rescues growth defects of Δget1get2 yeast. Ectopic expression of the cytosolic, positively charged N terminus is sufficient to block TA protein insertion in vitro. Our results collectively confirm that we have identified a plant-specific GET2 in Arabidopsis, and its sequence allows the analysis of cross-kingdom pathway conservation.
登录
查看更多内容
影响因子：
2.7
作者：
Grefen, Christopher;Blatt, Michael R.
通讯作者：
Blatt, Michael R.
DOI：
10.1073/pnas.1006036107
发表时间：
2010-07-06
影响因子：
11.1
作者：
Chartron, Justin W.;Suloway, Christian J. M.;Clemons, William M., Jr.
通讯作者：
Clemons, William M., Jr.
影响因子：
3
作者：
Karnik A;Karnik R;Grefen C
通讯作者：
Grefen C
影响因子：
4.8
作者：
Colombo, Sara Francesca;Cardani, Silvia;Borgese, Nica
通讯作者：
Borgese, Nica
影响因子：
5.8
作者：
Omasits, Ulrich;Ahrens, Christian H.;Wollscheid, Bernd
通讯作者：
Wollscheid, Bernd