copper ion binding; BEST Arabidopsis thaliana protein match is: unknown protein (TAIR:AT4G21140.1); Has 54 Blast hits to 54 proteins in 22 species: Archae - 8; Bacteria - 0; Metazoa - 1; Fungi - 0; Plants - 42; Viruses - 0; Other Eukaryotes - 3 (source: NCBI BLink).