Roof S K, Maguire M E
Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, OH 44106-4965.
J Am Coll Nutr. 1994 Oct;13(5):424-8. doi: 10.1080/07315724.1994.10718431.
Magnesium is unique among biological cations. Its volume change from hydrated cation to atomic ion is over an order of magnitude larger than that of any other biological cation. This volume change presents particular problems for a magnesium transport system and suggests that these systems may be significantly different from other classes of ion transport systems. Detailed study of Mg2+ transport in complex organisms is limited by severe technical problems. However, molecular genetic techniques have enabled the isolation of three Mg2+ transport systems from the Gram-negative bacterium Salmonella typhimurium. The MgtA and MgtB transport systems are members of the P-type ATPase superfamily of transporters but possess unique characteristics among members of this family. The CorA transport protein is the first member of an entirely new class of transport proteins. In addition, another completely new family of Mg2+ transport proteins have been identified that is present in both Gram-negative and Gram-positive bacteria. Characterization of these transporters should provide substantial insight into Mg2+ transport and cellular Mg2+ homeostasis.
镁在生物阳离子中独具特色。其从水合阳离子转变为原子离子时的体积变化比任何其他生物阳离子都大一个数量级以上。这种体积变化给镁转运系统带来了特殊问题，并表明这些系统可能与其他类别的离子转运系统有显著差异。对复杂生物体中镁离子转运的详细研究受到严重技术问题的限制。然而，分子遗传学技术已使得能够从革兰氏阴性菌鼠伤寒沙门氏菌中分离出三种镁离子转运系统。MgtA和MgtB转运系统是P型ATP酶转运蛋白超家族的成员，但在该家族成员中具有独特特征。CorA转运蛋白是一类全新转运蛋白中的首个成员。此外，还鉴定出了另一个全新的镁离子转运蛋白家族，它存在于革兰氏阴性菌和革兰氏阳性菌中。对这些转运蛋白的表征应能为镁离子转运和细胞内镁离子稳态提供深入见解。
