Metal sensing by the IRT1 transporter-receptor (Mol. Cell)

Plants need some but not too much iron, so the regulation of iron transporters is quite tight. IRT1 is a broad-spectrum metal transporter that is crucial for iron uptake (mutants can only be rescued by massive amounts of iron). IRT1 synthesis is transcriptionally upregulated by iron limitation, and although it is turned over by endocytosis, this turnover appears to be independent of iron levels. Dubeaux et al. showed that endocytosis and degradation of IRT1 is instead controlled by high levels of non-iron metals, such as manganese, cobalt and zinc. They further showed that the levels of non-iron metals are sensed directly by the IRT1 protein, through a stretch of histidine residues. Therefore, IRT1 serves as both a metal transporter and a receptor: a transcepter. (Summary by Mary Williams)  Mol. Cell 10.1016/j.molcel.2018.02.009