PHOSPHATE TRANSPORTER TRAFFIC FACILITATOR1 is a plant-specific SEC12-related protein that enables the endoplasmic reticulum exit of a high-affinity phosphate transporter in Arabidopsis
PHOSPHATE TRANSPORTER TRAFFIC FACILITATOR1 is a plant-specific SEC12-related protein that enables the endoplasmic reticulum exit of a high-affinity phosphate transporter in Arabidopsis
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DOI：
10.1105/tpc.105.036640
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发表时间：
2005-12-01
期刊：
影响因子：
11.6
通讯作者：
Paz-Ares, J
中科院分区：
文献类型：
--
作者：
González, E;Solano, R;Paz-Ares, J
磷酸盐转运蛋白1（PHT 1）基因编码磷酸盐转运蛋白，其在植物中的磷酸盐获取和再动员中起重要作用。拟南芥磷酸盐转运蛋白转运促进因子1（PHF 1）的突变损害了Pi的转运，导致许多Pi饥饿诱导基因的组成型表达，增加了砷酸盐抗性，并减少了Pi的积累。在所有组织中检测到PHF 1表达，特别是在根，花和衰老的叶子中，并且由Pi饥饿诱导，从而模仿整个PHT 1基因家族的表达模式。PHF 1定位于内质网（ER），PHF 1的突变导致ER滞留和质膜PHT 1; 1转运蛋白的积累减少。相比之下，PIP 2A质膜蛋白没有被错误定位，并且在突变体中Pi饥饿诱导的RNA酶的分泌没有受到影响。PHF 1编码一种植物特异性蛋白，其结构与早期分泌途径的SEC 12蛋白相关。然而，PHF 1缺乏SEC 12蛋白中作为鸟嘌呤核苷酸交换因子所必需的大部分保守残基。虽然它的功能在早期分泌贩运，PHF 1可能演变了一种新的机制，伴随着Pi转运蛋白的功能专业化。PHF 1的鉴定表明，植物也被赋予了特定的质膜蛋白，允许其退出ER的辅助蛋白，这些ER退出辅因子可能具有门特异性的起源。
PHOSPHATE TRANSPORTER1 (PHT1) genes encode phosphate (Pi) transporters that play a fundamental role in Pi acquisition and remobilization in plants. Mutation of the Arabidopsis thaliana PHOSPHATE TRANSPORTER TRAFFIC FACILITATOR1 (PHF1) impairs Pi transport, resulting in the constitutive expression of many Pi starvation-induced genes, increased arsenate resistance, and reduced Pi accumulation. PHF1 expression was detected in all tissues, particularly in roots, flowers, and senescing leaves, and was induced by Pi starvation, thus mimicking the expression patterns of the whole PHT1 gene family. PHF1 was localized in endoplasmic reticulum (ER), and mutation of PHF1 resulted in ER retention and reduced accumulation of the plasma membrane PHT1; 1 transporter. By contrast, the PIP2A plasma membrane protein was not mislocalized, and the secretion of Pi starvation-induced RNases was not affected in the mutant. PHF1 encodes a plant-specific protein structurally related to the SEC12 proteins of the early secretory pathway. However, PHF1 lacks most of the conserved residues in SEC12 proteins essential as guanine nucleotide exchange factors. Although it functions in early secretory trafficking, PHF1 likely evolved a novel mechanism accompanying functional specialization on Pi transporters. The identification of PHF1 reveals that plants are also endowed with accessory proteins specific for selected plasma membrane proteins, allowing their exit from the ER, and that these ER exit cofactors may have a phylum-specific origin.