Answer: The p53 gene codes for a protein that helps to suppress the growth of tumors in the body. Changes in p53 gene that result in the production of different p53 protein variants can increase cancer risk. The table shows three p53 protein variants, p53(a), p53(b), and p53(c), and how they differ in their amino acid composition.
The amino acid sequence of a protein determines its 3D structure and function. In p53(a), the last two amino acids are Glu and Asp, respectively. In p53(b), the last two amino acids are Arg and missing, respectively. In p53(c), the last two amino acids are Asp and Gly, respectively. These changes in amino acid sequence result in changes in the shape and charge of the p53 protein.
The charge of a protein is determined by the type of amino acids it contains. In p53(a), the last two amino acids are negatively charged, which makes the protein more stable and better able to bind to DNA. In p53(b), the last amino acid is positively charged, which makes the protein less stable and less able to bind to DNA. In p53(c), the last amino acid is neutral, which makes the protein less stable and less able to bind to DNA.
These changes in the shape and charge of the p53 protein can affect its ability to bind to DNA and regulate cell growth. When p53 is not functioning properly, cells can divide uncontrollably and form tumors. Therefore, changes in p53 gene that result in the production of different p53 protein variants can increase cancer risk.