Final answer:
The most well documented monomeric G-protein is the Ras protein, which acts as a molecular switch inside cells, participating in various cellular processes and signal transduction pathways. It is activated by GDP/GTP exchange, similar to heterotrimeric G-proteins, and deactivated by GTP hydrolysis.
Step-by-step explanation:
The most well documented monomeric G-protein is the Ras protein. Monomeric G-proteins, also known as small GTPases, are critical for various cellular processes, including growth, differentiation, and intracellular trafficking. They act as molecular switches inside cells, activated when GDP (guanosine diphosphate) is exchanged for GTP (guanosine triphosphate). Although the text refers to heterotrimeric G-proteins in the context of adenylyl cyclase activation by a Gs protein, monomeric G-proteins like Ras have similar GDP/GTP exchange mechanisms.
In cell signaling, G-protein-linked receptors bind to a ligand and subsequently activate a G-protein, which can be either heterotrimeric or monomeric like Ras. This activated G-protein then interacts with other cellular components to elicit a response, such as opening an ion channel or activating an enzyme, like adenylate cyclase.
When hydrolysis of GTP to GDP occurs, the signal is terminated, resetting the G-protein to its inactive state. This cyclic series of events ensures that cellular signals are tightly regulated and that the cellular responses are appropriately controlled.