Köck M, Löffler A, Abel S, Glund K
Martin-Luther-Universität Halle-Wittenberg, Institut für Biochemie, Abteilung für Allgemeine und Pflanzenbiochemie, Halle/Saale, Germany.
Plant Mol Biol. 1995 Feb;27(3):477-85. doi: 10.1007/BF00019315.
In previous work we have determined the primary structure of two of the five ribonucleases which are induced by phosphate starvation in cultured tomato cells. Here, we present the isolation and characterization of the cDNAs for the extracellular ribonuclease LE and the intracellular, but extravacuolar ribonuclease LX. Structural analysis of these cDNAs together with partial protein-sequencing of vacuolar ribonucleases LV1, LV2 and LV3 revealed a family of very similar ribonucleases. From these data we assume identify between ribonucleases LE and LV3 for which the targeting mechanism has to be shown. Furthermore, RNase LV1 and RNase LV2 might be posttranslational processing products of RNase LX which travel to the vacuoles after splitting off the putative ER retention signal present at RNase LX. Additionally, we show by northern blot analysis that phosphate starvation in plant cells leads to an increase in the steady-state level of this type of enzymes revealing close similarities of the plant response to a limited supply of inorganic phosphate with the PHO regulation in bacteria and fungi.
在之前的工作中，我们已经确定了培养的番茄细胞中由磷酸盐饥饿诱导产生的五种核糖核酸酶中的两种的一级结构。在此，我们展示了细胞外核糖核酸酶LE和细胞内但液泡外核糖核酸酶LX的cDNA的分离和特性。对这些cDNA的结构分析以及液泡核糖核酸酶LV1、LV2和LV3的部分蛋白质测序揭示了一个非常相似的核糖核酸酶家族。根据这些数据，我们假设核糖核酸酶LE和LV3之间存在一致性，其靶向机制有待阐明。此外，核糖核酸酶LV1和核糖核酸酶LV2可能是核糖核酸酶LX的翻译后加工产物，在去除核糖核酸酶LX上存在的假定内质网滞留信号后进入液泡。此外，我们通过Northern印迹分析表明，植物细胞中的磷酸盐饥饿导致这类酶的稳态水平增加，揭示了植物对无机磷酸盐供应有限的反应与细菌和真菌中的PHO调节有密切相似性。
