**14. Conclusion**

MTs are stress related protein and might be involved in essential metal homeostasis and detoxification of excess metals during organism's developmental process. The MT genes are readily induced by several toxicologic and physiologic stimuli. Due to the cysteines in MT are absolutely conserved across the species, it is suspected that cysteines are essential for the function and MT is required for the life. A clear role for MTs is yet to be established, although they are certainly thought to play a key role in the metal metabolism. MTs may function as the antioxidants and another possibility is the role in repair of the plasma membrane. Although MTs are expressed ubiquitously and conserved in living organisms, determining their function remains a future challenge. So further research work is necessary to better understand MT-metal interaction, the mechanism of MT expression and molecular transformation of novel MT genes to plant and microbial system for increasing heavy metal detoxification in the environment.
