Final answer:
In normal cells, p53, a tumor suppressor gene, promotes its own degradation by activating gene transcription of a protein known as E6AP, which marks p53 for degradation, maintaining cell cycle balance.
Step-by-step explanation:
p53-dependent Transcription and Cell Cycle Regulation
In normal cells, p53 is a crucial protein that functions as a tumor suppressor gene by regulating the cell cycle at the G1 checkpoint. The role of p53 involves activating genes that halt the cycle, allowing time for DNA repair, or initiating cell death when repair is not possible. Mutations in the p53 gene are associated with various types of cancers, as they lead to the production of a defective p53 protein that cannot effectively prevent the propagation of mutated cells.
To maintain cellular homeostasis, normal p53 also promotes its own degradation by activating the transcription of specific genes. This process is a feedback mechanism that prevents excessive p53 activity once its role is fulfilled. In normal cell functioning, one such gene influenced by p53 is the E6-associated protein (E6AP), which, when bound to p53, marks it for degradation.
Thus, in normal cells, p53-dependent transcription of E6AP promotes p53 degradation, balancing the cell's response to DNA damage and ensuring proper cell cycle progression. The malfunction of this balance can lead to unregulated cell growth and the development of cancer.