SLC41A1 Is a Novel Mammalian Mg2 Carrier*

The molecular biology of mammalian magnesium transport-ers and their interrelations in cellular magnesium homeostasis are largely unknown. Recently, themouse SLC41A1 proteinwas suggested to be a candidate magnesium transporter with chan-nel-like properties when overexpressed in Xenopus laevis oocytes. Here, we demonstrate that human SLC41A1 overex-pressed inHEK293 cells forms protein complexes and locates to the plasma membrane without, however, giving rise to any detectable magnesium currents during whole cell patch clamp experiments. Nevertheless, in a strain of Salmonella enterica exhibiting disruption of all three distinct magnesium transport systems (CorA, MgtA, and MgtB), overexpression of human SLC41A1 functionally substitutes these transporters and restores the growth of the mutant bacteria at magnesium con-centrations otherwisenon-permissive for growth.Thus,wehav