The calcium-binding activity of a vacuole-associated, dehydrin-like protein is regulated by phosphorylation
The calcium-binding activity of a vacuole-associated, dehydrin-like protein is regulated by phosphorylation
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DOI：
10.1104/pp.002550
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发表时间：
2002-10-01
期刊：
影响因子：
7.4
通讯作者：
Randall, SK
中科院分区：
文献类型：
--
作者：
Heyen, BJ;Alsheikh, MK;Randall, SK
从芹菜（Apium graveolens）中分离纯化了一个表观分子量为45 kD的液泡膜钙结合蛋白。这种蛋白质VCaB 45富含于高度空泡化的组织中，并位于空泡腔内。抗原相关蛋白存在于许多双子叶植物中。VCaB45含有与Bclin家族特征基序显著的氨基酸同一性，与Bclin抗原相关，并且具有与Bclin相似的多种生化性质。VCaB 45在十二烷基硫酸钠-聚丙烯酰胺凝胶电泳中迁移，表观分子量为45 kD。通过基质辅助激光解吸电离飞行时间测定的真实质量为16.45 kD。VCaB 45对钙有两个特征解离常数，分别为0.22 +/-0.142 mm和0.64 +/-0.08 mm，每个蛋白质估计有24.7 +/-11.7个钙结合位点。VCaB45的钙结合特性受磷酸化调节;磷酸化蛋白质结合的钙比去磷酸化蛋白质多100倍。VCaB 45是酪蛋白激酶II（一种普遍存在的真核激酶）的"体外"底物，磷酸化导致钙结合活性的部分活化。VCaB 45的液泡定位、钙结合和磷酸化提示其潜在的功能。
A vacuole membrane-associated calcium-binding protein with an apparent mass of 45 kD was purified from celery (Apium graveolens). This protein, VCaB45, is enriched in highly vacuolate tissues and is located within the lumen of vacuoles. Antigenically related proteins are present in many dicotyledonous plants. VCaB45 contains significant amino acid identity with the dehydrin family signature motif, is antigenically related to dehydrins, and has a variety of biochemical properties similar to dehydrins. VCaB45 migrates anomalously in sodium dodecyl sulfate-polyacrylamide gel electrophoresis having an apparent molecular mass of 45 kD. The true mass as determined by matrix-assisted laser-desorption ionization time of flight was 16.45 kD. VCaB45 has two characteristic dissociation constants for calcium of 0.22 +/- 0.142 mm and 0.64 +/- 0.08 mm, and has an estimated 24.7 +/- 11.7 calcium-binding sites per protein. The calcium-binding properties of VCaB45 are modulated by phosphorylation; the phosphorylated protein binds up to 100-fold more calcium than the dephosphorylated protein. VCaB45 is an "in vitro" substrate of casein kinase II (a ubiquitous eukaryotic kinase), the phosphorylation resulting in a partial activation of calcium-binding activity. The vacuole localization, calcium binding, and phosphorylation of VCaB45 suggest potential functions.