Heavy-metal-binding protein. Binds lead, cadmium and copper. May be involved in heavy-metal transport (PubMed:18823312). May be involved in cadmium transport and play a role in cadmium detoxification (PubMed:21072340). Interacts with ZHD11/HB29 and ACBP2 (via ankyrin repeats). May also interact with HB21. PubMed:18974936 shows that isopernylation may be important for a speckle-like nuclear localization in a heterologous system, while PubMed:18823312 shows a plasma membrane localization. Expressed in roots, stems and flowers. Lower expression in siliques and leaves. Expressed in the vascular tissues. Detected in lateral roots, shoot apical meristem, petals of unopened flowers and weak expression in leaf vasculature. Up-regulated by cadmium and zinc, but not by lead or copper. Up-regulated by cold, drought and salt stress. Not induced by abscisic acid or by leaf senescence. No visible phenotype. Inhibition of HB29-dependent induction of stress-related target genes. Belongs to the HIPP family.