Protein synthesis suppressor genes

Nucleic acids in the DNA contain a high number of nucleophilic sites that can be attacked by electrophilic intermediates (metabolites) of chemical compounds. DNA adducts formed may cause alterations in the expression of a critical gene in the cell and thus lead to cell death. For example, modification of p53 tumor suppressor gene may inactivate the functions of the p53 protein and render cells sensitive to malignant transformation. Also, formation of RNA adducts may inhibit key cellular events because RNA is essential for protein synthesis. 

The p53 gene is a tumor suppressor gene, which means that its activity stops the formation of tumors via the production of p53 protein. As shown in the picture below, the p53 protein has four identical chains, which are joined together by a central tetramerization domain. The p53 protein molecule wraps around and binds DNA.This wrapping action then turns on another gene, which codes for a 21-kDa protein that regulates DNA synthesis. 

In the processes of cell DNA damage repair, bcl-2 and p53 are two of the most important proteins encoded by the bcl-2 gene and p53 tumor suppressor gene. Wild-type p53 can suppress cell proliferation and slow DNA synthesis and block transition from G1 to S phase of the cell cycle. The bcl-2 gene is a proto-oncogene and the most important inhibitor of apoptosis. Expression of bcl-2 may interfere with the apoptotic... 

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