This family consists of metallothioneins from several worm and sea urchin species. Metallothioneins are low molecular weight, cysteine rich proteins known to be involved in heavy metal detoxification and homeostasis [1].

1: The identification, cloning and characterization of earthworm metallothionein. Sturzenbaum SR, Kille P, Morgan AJ; FEBS Lett 1998;431:437-442. PMID:9714559