2.A.55.2.18
NRAMP4 of 512 aas and 12 TMSs, a vacuolar metal transporter involved in intracellular metal homeostasis. It can transport iron (Fe), manganese (Mn) and cadmium (Cd), and regulates metal accumulation under Fe starvation. It acts redundantly with NRAMP3 (which is 85% identical to it) to mobilize vacuolar Fe and provide sufficient Fe during seed germination (Lanquar et al. 2005). In association with NRAMP3, it is required for optimal growth and photosynthesis under Mn deficiency. It exports Mn from vacuoles in leaf mesophyll cells, making Mn available for functional photosystem II in chloroplasts (Lanquar et al. 2010). Its ortholog in Thlaspi japonicum has been characterized (Mizuno et al. 2005). Expression of particular transmembrane transporters (e.g., members of the ZIP (ZNT1) and NRAMP (NRAMP4) families) leads to metal tolerance and accumulation in plants (Fasani et al. 2021).