钙依赖型蛋白激酶调节保卫细胞膜内向钾离子通道的实验证据  

EVIDENCES FOR REGULATION OF THE INWARD K + CHANNELS BY CDPK IN VICIA FABA GUARD CELLS 

作　　者：王喜庆 武维华[1,2] 张继澍[1,2] 

机构地区：[1]中国农业大学生物学院植物生理生化系 [2]西北农业大学基础科学系

出　　处：《Acta Botanica Sinica》1998年第11期1001-1009,共9页Acta Botanica Sinica（植物学报：英文版）

摘　　要：保卫细胞内钙离子浓度的变化对气孔保卫细胞质膜上的内向钾离子通道活性有显著调节作用，而钾离子通道活性的变化可导致细胞渗透压的改变，进而调节气孔的开闭运动。然而，钙离子通过何种机制实现对钾离子通道的调节尚不清楚。作者利用膜片钳全细胞记录方法探讨了钙依赖型蛋白激酶（ＣＤＰＫ）是否参与了钙离子调节保卫细胞钾离子通道的信号转导过程。当胞内钙离子浓度为１．５μｍｏｌ／Ｌ时，保卫细胞全细胞内向钾电流被抑制约６０％；同时加入ＣＤＰＫ的底物组蛋白ⅢＳ或ＣＤＰＫ的底物竞争性抑制剂鱼精蛋白可完全逆转钙离子的作用；但在胞内同时加入纯化的ＣＤＰＫ蛋白则可进一步促进钙离子对保卫细胞内向钾电流的抑制。研究结果初步证明。Regulation of the inward K + channels in the guard cell plasma membranes plays important roles in regulation of stomatal movement in responses to exogenous and endogenous signals. It is well known that elevation of cytosolic Ca 2+ in guard cells inactivates these inward K + channels, and consequently inhibits stomatal opening or induces stomatal closing, yet the downstream molecular mechanism for the Ca 2+ mediated inhibition of the inward K + channels remains unknown. The calmodulin like domain protein kinases (CDPKs) have been identified as an unique group of protein kinases in higher plant cells. As a downstream regulator, CDPK may play roles in mediating Ca 2+ regulation on the inward K + channels in stomatal guard cells. The authors have applied the patch clamp technique to investigate if CDPK be involved in the regulation of the inward K + channels in Vicia faba guard cells by cytosolic Ca 2+ . The presence of the 1.5 μmol/L intracellular Ca 2+ resulted in inhibition of the inward K + channel activity by 60%, while the addition of purified CDPK from the cytoplasmic side resulted in greater inhibition than Ca 2+ alone. Histone Ⅲ S and protamine, which is the substrate and substrate competitive inhibitor of CDPKs respectively, completely reversed the Ca 2+ induced inhibition of the inward K + channel activities. These results are the first reported evidences for that CDPKs are involved in the Ca 2+ mediated inward K + channel regulation in guard cells.

关 键 词：保卫细胞 钾通道 信号转导 磷酸化 CDPK 

分 类 号：Q73[生物学—分子生物学] Q942.5