[Structure and function of tonoplast Cation/H+ antiporters in plant: a review].

Cation transporters play important roles in modulating the concentration of intracellular metal ions. The vacuole is an important storage organelle for many ions. Cation (Ca)/H antiporters (CAXs) located at vacuolar membrane are mainly involved in the Ca flux into the vacuole, and appear to be capable of transporting various divalent cations to some degree. Several CAX genes have been isolated and characterized from various plants in recent years. Four domains of plant CAXs have been identified: NRR regulates Ca transport by a mechanism of N-terminal autoinhibition; Ca domain and C domain confer Ca 张玉秀等: 植物液泡膜阳离子/H反向转运蛋白结构和功能研究进展 547 Journals.im.ac.cn and Mn specificity among CAX transporters, respectively; D domain plays a part in the regulation of cytosolic pH. AtCAXs identified in Arabidopsis thaliana are involved in the growth, development and stress adaption of plant. AtCAX3 is the mainly Ca/H transporter in response to salt stress; AtCAX2 and AtCAX4 participate in transportation and detoxicification of heavy metal ions (Cd, Zn, and Mn) in cells under heavy metal stress, and impact root/shoot Cd partitioning in plant. These suggest that CAX genes may be useful for nutritional enhancement of plants, and for increasing phytoremediation potential. Here, the classification, structure and function of CAXs in plants are reviewed.