The bifunctional transporter-receptor IRT1 at the heart of metal sensing and signalling.

Transporters are at the centre of regulatory modules allowing optimal assimilation, distribution or efflux of substrate molecules. The IRT1 root metal transporter represents a textbook example in which detailed regulatory networks have been shown to integrate several endogenous and exogenous cues at various levels to regulate its expression and to fine tune iron uptake. Here, we summarise recent advances in the dissection of the transcriptional and posttranslational control of IRT1 by its various metals substrates and discuss the emerging role of IRT1 in the direct sensing of non-iron metals flowing through IRT1 to drive its degradation. We propose that transporters that also act as receptors are likely to be a common theme in the regulation of nutrient transport by sensing local nutrient concentrations.