Zinc a major trace element; perform diverse roles in genetics and physiology in almost every vital body system of the mammalian body. Zinc regulates the expression of almost all essential genes responsible for performing pivotal functions in mammal cells through provision of structural integrity to the major transcriptional factors Zn finger Proteins (ZnF) and gene regulation for production of metallothionein protein. Zinc performed at least eight vital functions in living organisms including gene regulation e.g., as a promoter through metal response elements, structural i.e. zinc-finger motifs, catalytic e.g., metalloenzymes, DNA and RNA polymerase, DNA replication, Growth promotion, antioxidant, regulate functions of central nervous system and also act as hepato-protectant and detoxifying agent. Almost all of these vital functions are regulated through metallothionein protein, a cysteine rich Zn binding protein. These functions are basic mechanism for sustaining life. Therefore, this review paper was planned with the objective to highlight the important functions of Zn inside the mammal's body with particular reference to the metallothionein protein. Bioinformatics study performed for estimation of conservation and evolution of this important protein shows its greater conservancies in six important mammalian species.