Final answer:
Monomeric GTP-binding proteins are regulated by GTPase-activating proteins (GAPs) and guanine nucleotide exchange factors (GEFs). GAPs turn off the G-protein activity by accelerating the hydrolysis of GTP to GDP, while GEFs activate it by facilitating GDP-GTP exchange. This regulatory mechanism is essential for proper cell signalling and function.
Step-by-step explanation:
The activity of monomeric GTP-binding proteins, also known as monomeric G-proteins, is regulated by two types of regulatory proteins, GTPase-activating proteins (GAPs), and guanine nucleotide exchange factors (GEFs). GAPs accelerate the hydrolysis of GTP to GDP, which turns off the G-protein, while GEFs promote the release of GDP to allow the binding of GTP, thereby activating the G-protein. The cycle of activation and deactivation is crucial to control various cellular processes, including cell growth, differentiation, and movement.
Monomeric G-proteins are involved in cell signalling and are activated when a signalling molecule binds to a G-protein-coupled receptor (GPCR) on the cell surface. This binding causes a GDP molecule associated with the protein to be exchanged for GTP, thus activating the G-protein. The activated G-protein then has the capability of triggering other cellular components, which leads to the desired cellular response. Eventually, the GTP is hydrolyzed back to GDP which deactivates the G-protein, completing the cycle.