Chapter fourteen – the mechanisms of Mg2+ and Co2+ transport by the CorA family of divalent cation transporters

The metal ions Mg2+ and Co2+ are essential for life, although to different degree. They have similar chemical and physical properties, but their slight differences result in Mg2+ to be the most abundant metal ion in living cells and the trace element Co2+ being toxic at relatively low concentrations. Specialized transporters have evolved in living cells to supply and balance the Mg2+ and Co2+ need of the cells. The current knowledge of the molecular mechanisms of Mg2+ and Co2+ -specific transporters is very limited at this point. Recently, there has been remarkable advances to understand the CorA family, a family of transporters that are able to transport both ions. These new data have increased our insights in how Mg2+ and Co2+ are translocated across membranes. Presently, CorA is probably the best system to study the mechanisms of Mg2+ and Co2+ transport. This chapter discusses the mechanisms through which CorA selects, transports, and regulates the translocation of its substrate. In addition, we highlight the physical and chemical properties of the substrates, which are important parameters required for better understanding of the transporter action