Final answer:
The percentage of p53 missense point mutations is not explicitly stated, but mutated p53 genes, which include missense mutations, are present in over half of all human tumors. Missense mutations alter the amino acid sequence of the p53 protein, impairing its function as a tumor suppressor and potentially leading to unregulated cell proliferation and decreased apoptosis.
Step-by-step explanation:
The question you've asked is about the percentage of missense point mutations in mutated p53 genes. Missense mutations are a type of point mutation where a single nucleotide change results in a different amino acid being incorporated into a protein. In the case of p53, which is a tumor suppressor protein, these mutations can have significant implications for the development of cancer.
Although the exact percentage of p53 missense mutations varies by tumor type, mutated p53 genes have been identified in more than half of all human tumor cells. These mutations can result in a faulty p53 that may fail to detect errors in genomic DNA or signal DNA repair enzymes, consequently damaged DNA remains uncorrected and the cell may continue to divide and accumulate new mutations. If p53 is unable to trigger programmed cell death, this can lead to the propagation of cancer cells. Specifically, literature such as the study by G.P. Pfeifer et al. in Nature, referenced above, quantitatively details the mutation signatures of p53 in different cancer types but does not provide an overall proportion specifically for missense mutations. However, the index referencing a missense mutation numbers '429' and '667', may infer extensive records on the p53 missense mutations within cancer cells.