The Pmr1 protein, the major yeast Ca2+-ATPase in the Golgi, regulates intracellular levels of the cadmium ion

Cadmium is a nonessential, highly toxic heavy metal that shows ionic properties similar to calcium. These ionic similarities imply that the cadmium ion, Cd2+, is a calcium ion, Ca2+, receptor-agonist, affecting the same biochemical pathways involved in Ca2+ homeostasis. In the yeast Saccharomyces cerevisiae, the PMC1 and PMR1 genes encode vacuolar and Golgi Ca2+-ATPases, respectively. The PMR1 protein product Pmr1p is involved in both Ca2+ and Mn2+ homeostasis. This study investigated the importance of Pmc1p and Pmr1p for Cd2+ cellular detoxification. Using the standard techniques of yeast molecular research and a multielemental procedure named particle-induced X-ray emission, Pmr1p was identified as a protein that directly participates in the detoxification of Cd2+, possibly through the secretory pathway. The results allow us to posit a model of Cd2+ detoxification where Pmr1p has a central role in cell survival in a Cd2+-rich environment.