Question

A patient has just been diagnosed with cancer and genetic analysis shows that the cancer cells contain a mutation in the RAS proto-oncogene. Explain why RAS can function as an oncogene and the effect that this mutation is likely to have on Ras protein function.

Answer 1

Step-by-step explanation:

Proto-oncogenes are genes that have the potential to turn normal cells to cancer cells if they mutate. Once they have a mutation, they are called oncogenes. These typically code for proteins that control the cell cycle and cell growth.

Ras proteins are intracellular, and act as molecular switches that can be inactive or active. If they are inactive and receive a signal from the extracellular space indicating that the cell has to grow, they bind GTP and become activated. Once active, they send further signals that stimulate cell proliferation and division. After a while of sending those signals, the Ras protein hydrolizes GTP to GDP because it has an intrinsic GTPase activity, and becomes inactive once again, stopping the growth signal.

Mutations in the Ras oncogene typically affect the GTPase activity, causing its loss of function and subsequently that the Ras protein stays permanently active. This, in turn, causes uncontrollable cell proliferation, characteristic of cancer.