Final answer:
Ras is activated when bound to GTP, triggering the MAPK kinase cascade. Mutations that inhibit Ras GTPase activity result in uncontrolled cell proliferation, often leading to cancer.
Step-by-step explanation:
The Ras protein is a small GTPase that plays a critical role in cell signal transduction pathways. When Ras is bound to guanosine triphosphate (GTP), it becomes activated and initiates a series .
This cascade involves the activation of RAF, which phosphorylates and activates MEK, which in turn phosphorylates and activates ERK.
The activated ERK can then enter the nucleus and trigger various cellular responses, including cell proliferation and differentiation.
In some cancers, mutations in the Ras protein inhibit its GTPase activity, preventing Ras from hydrolyzing GTP to guanosine diphosphate (GDP).
This impairment causes Ras to remain in its Outbound, active state perpetually, leading to uncontrolled cell proliferation, as Ras continuously signals for cell growth and division without regulation.
Such mutations in Ras are highly associated with the development of various cancers and highlight the importance of tight regulation of Ras activity in normal cell function.