text: The earliest research showing that yeast takes up Mg appears to be done by Schmidt et al. (1949). However, these authors only showed altered yeast Mg content in a table within the paper, and the report's conclusions dealt entirely with the metabolism of phosphate. A series of experiments by Rothstein shifted the focus more towards the uptake of the metal cations, showing that yeast take up cations with the following affinity series; Mg, Co, Zn > Mn > Ni > Ca > Sr. Additionally, it was suggested that the transport of the different cations is mediated by the same transport system — a situation very much like that in bacteria.
  In 1998, MacDiarmid and Gardner finally identified the proteins responsible for the observed cation transport phenotype in Saccharomyces cerevisiae. The genes involved in this system and a second mitochondrial Mg transport system, functionally identified significantly after the gene was cloned, are described in the sections below.