Question

Ligand binds to the G-protein coupled receptor which activates it, the activated receptor causes Ras to bind to GTP which activates it, Ras then activates other proteins further down the signal transduction pathway, after this, Ras hydrolyses GTP back to GDP which inactivates Ras. Ras can then be activated the next time the receptor binds its ligand?

Answer 1

In cell signaling, G-protein-coupled receptors activate G-proteins which then initiate other cellular processes; faulty GTP hydrolysis due to Ras mutations can lead to cancer.

Step-by-step explanation:

Cell signaling through G-protein-coupled receptors is a vital biological process that follows a cyclic pattern. Initially, an inactive G-protein binds to a receptor that changes shape upon ligand attachment. This process causes the G-protein to release GDP (guanosine diphosphate) and acquire GTP (guanosine triphosphate), thus becoming activated. Subsequently, the G-protein's subunits a and By dissociate; either one or both fragments are capable of activating further downstream proteins within the cell. Over time, the GTP on the active ‘a’ subunit is hydrolyzed back into GDP, effectively inactivating the subunit, and the By subunit also becomes deactivated. The subunits then recombine to form the original inactive G-protein, ready to restart the cycle when a new ligand binds to the receptor.

The importance of this process is underscored by the observation that Ras, a type of G-protein, plays a key role in many signaling pathways related to cell growth and differentiation, and mutations in Ras can lead to cancer by allowing unregulated cell proliferation due to a failure to hydrolyze GTP properly.