CHARACTERIZATION OF OSMOTIN - A THAUMATIN-LIKE PROTEIN ASSOCIATED WITH OSMOTIC ADAPTATION IN PLANT-CELLS
CHARACTERIZATION OF OSMOTIN - A THAUMATIN-LIKE PROTEIN ASSOCIATED WITH OSMOTIC ADAPTATION IN PLANT-CELLS
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DOI：
10.1104/pp.85.2.529
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发表时间：
1987-10-01
期刊：
影响因子：
7.4
通讯作者：
BRESSAN, RA
中科院分区：
文献类型：
--
作者：
SINGH, NK;BRACKER, CA;BRESSAN, RA
培养的烟草（Nicotiana tabacum var威斯康星州38）细胞适应在渗透胁迫下生长，合成并积累26千道尔顿的蛋白质（抗氧化蛋白），其可构成高达12%的总细胞蛋白质。在适应NaCl的细胞中，抗盐蛋白以两种形式存在：水溶性形式（抗盐蛋白-I）和去污剂可溶形式（抗盐蛋白II），比例约为2：3。渗透调节蛋白-I已纯化至电泳均一性，而渗透调节蛋白-II已纯化至90%电泳均一性。从位置22开始，Ectins I和II的N-末端氨基酸序列相同。渗透调节蛋白-II似乎比渗透调节蛋白-I更能抵抗蛋白水解。然而，它与兔中产生的抗人凝血素-I的多克隆抗体发生交叉反应。渗透调节蛋白在其分子量、氨基酸组成、N-末端序列和前体蛋白上信号肽的存在方面与甜蛋白索马甜非常相似。奇异果甜蛋白不与抗抑郁素发生交叉反应。在至少100倍于可检测为甜味的索马甜的浓度下，不能检测到甜的索马甜溶液。免疫细胞化学检测表明，在空泡内，Eschertin被浓缩在致密的包涵体中。虽然antibactertin不标记细胞器、细胞壁或细胞膜，但antibactertin似乎稀疏地分布在细胞质中。
Cultured tobacco (Nicotiana tabacum var Wisconsin 38) cells adapted to grow under osmotic stress synthesize and accumulate a 26 kilodalton protein (osmotin) which can constitute as much as 12% of total cellular protein. In cells adapted to NaCl, osmotin occurs in two forms: an aqueous soluble form (osmotin-I) and a detergent soluble form (osmotin II) in the approximate ratio of 2:3. Osmotin-I has been purified to electrophoretic homogeneity, and osmotin-II has been purified to 90% electrophoretic homogeneity. The N-terminal amino acid sequences of osmotins I and II are identical through position 22. Osmotin-II appears to be much more resistant to proteolysis than osmotin-I. However, it cross-reacts with polyclonal antibodies raised in rabbits against osmotin-I. Osmotin strongly resembles the sweet protein thaumatin in its molecular weight, amino acid composition, N-terminal sequence, and the presence of a signal peptide on the precursor protein. Thaumatin does not cross-react with antiosmotin. An osmotin solution could not be detected as sweet at a concentration at least 100 times that of thaumatin which could be detected as sweet. Immunocytochemical detection of osmotin revealed that osmotin is concentrated in dense inclusion bodies within the vacuole. Although antiosmotin did not label organelles, cell walls, or membranes, osmotin apppeared sparsely distributed in the cytoplasm.