Final answer:
Inhibited GTPase activity of the RAS protein, due to certain cancerous mutations, prevents the conversion of GTP into GDP.
Step-by-step explanation:
In the context of cell signaling, the RAS G-protein plays a crucial role. It operates like a molecular switch toggling between an active and inactive state, coordinating a series of downstream cellular processes. When RAS is bound to guanosine triphosphate (GTP), it is in an active state, and when bound to guanosine diphosphate (GDP), it is inactive. Normally, the intrinsic GTPase activity of the RAS protein hydrolyzes GTP to GDP, thereby switching itself off.
In certain cancerous mutations, the GTPase activity of the RAS protein is disrupted, meaning the RAS protein can no longer hydrolyze GTP into GDP. This results in the RAS protein remaining perpetually active. Consequently, the signal for cell growth and proliferation remains on, leading to uncontrolled cell division and the potential for tumor growth and cancer progression. This aberration significantly affects downstream cellular events such as cell cycle progression, growth and differentiation.