Martín M L, Busconi L
Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), Centro de Investigaciones Biológicas, Fundación para Investigaciones Biológicas Aplicadas, Mar del Plata, Argentina.
Plant J. 2000 Nov;24(4):429-35. doi: 10.1046/j.1365-313x.2000.00889.x.
Calcium-dependent protein kinases (CDPKs), the most abundant serine/threonine kinases in plants, are found in various subcellular localizations, which suggests that this family of kinases may be involved in multiple signal transduction pathways. A complete analysis to try to understand the molecular basis of the presence of CDPKs in various localizations in the cell has not been accomplished yet. It has been suggested that myristoylation may be responsible for membrane association of CDPKs. In this study, we used a rice CDPK, OSCPK2, which has a consensus sequence for myristoylation at the N-terminus, to address this question. We expressed wild-type OSCPK2 and various mutants in different heterologous systems to investigate the factors that affect its membrane association. The results show that OSCPK2 is myristoylated and palmitoylated and targeted to the membrane fraction. Both modifications are required, myristoylation being essential for membrane localization and palmitoylation for its full association. The fact that palmitoylation is a reversible modification may provide a mechanism for regulation of the subcellular localization. OSCPK2 is the first CDPK shown to be targeted to membranes by an src homology domain 4 (SH4) located at the N-terminus of the molecule.
钙依赖蛋白激酶（CDPKs）是植物中最丰富的丝氨酸/苏氨酸激酶，存在于各种亚细胞定位中，这表明该激酶家族可能参与多种信号转导途径。目前尚未完成全面分析以试图了解CDPKs在细胞中各种定位存在的分子基础。有人提出肉豆蔻酰化可能负责CDPKs与膜的结合。在本研究中，我们使用了一种水稻CDPK，即OSCPK2，其在N端具有肉豆蔻酰化的共有序列，以解决这个问题。我们在不同的异源系统中表达野生型OSCPK2和各种突变体，以研究影响其与膜结合的因素。结果表明，OSCPK2发生了肉豆蔻酰化和棕榈酰化，并定位于膜部分。这两种修饰都是必需的，肉豆蔻酰化对于膜定位至关重要，而棕榈酰化对于其完全结合至关重要。棕榈酰化是一种可逆修饰这一事实可能为亚细胞定位的调节提供一种机制。OSCPK2是第一个被证明通过位于分子N端的src同源结构域4（SH4）定位于膜的CDPK。
