Mg2+ plays a vital role as a co-factor for many enzymes and is an essential structural element of proteins and nucleic acids and a modulator of ion channels.
Plasma [Mg2+] in most species is 0.9–1 mM and the free intracellular [Mg2+] ([Mg2+]i) in cells has been estimated to be 0.5–1 mM [12, 30, 45] so that mammalian cells lack a substantial transmembrane chemical gradient for Mg2+ and thus the movement of Mg2+ into the cell is driven primarily by the electrical gradient. At present, our mechanistic understanding of these phenomena is incomplete, because the molecular events controlling Mg2+ transport pathways have eluded detailed analysis, in particular since the specific proteins involved in Mg2+ uptake have long eludes identification and characterization. In recent years,
however, significant progress has been made towards the isolation of genes (and their products) involved directly in transporting Mg2+ across biological membranes in mammalian cells. Recent evidence obtained in heterologous expression systems suggests that the products of at least two members of the conserved Mg2+ transporter-E (MgtE) gene family, SLC41A1 and SLC41A2, as well as the novel protein Mg2+ transporter 1 (MagT1) are integral plasma membrane proteins responsible for Mg2+ uptake.