Metallothioneins have a high content of cysteine residues that bind various heavy metals (Probable). Functions as metal chelator of copper (Cu) and zinc (Zn) (PubMed:18287486). Plays a role in Cu homeostasis, specifically in the remobilization of Cu from senescing leaves. The mobilization of Cu from internal sources is important for seed development (PubMed:24635746). Abundant in leaves, inflorescences and roots of mature plants. Also detected in roots of young plants, and in siliques (PubMed:7565594). Expressed in leaf mesophyll cells, filaments, stigma and tips of elongating lateral roots (Ref.8). Strongly induced in seedlings by CuSO4. Belongs to the metallothionein superfamily. Type 15 family.