Involved in resistance to abiotic stress. Confers resistance to heavy metal ions (e.g. cadmium (CdCl(2)) and copper (CuCl(2))) by chelating them at the plasma membrane of root cells, thus stopping their entry and reducing their accumulation. Heterodimers (PubMed:29272523). Binds weakly to CYSTM7 and WIH1/CYSTM13 (PubMed:29272523). Mostly expressed in stems, siliques, leaves and flowers and, to a lower extent, in roots. Induced by salt, cold and drought. Belongs to the CYSTM1 family.