Which proteins enhance GTPase activity in GPCR signaling?

In GPCR (G-protein-coupled receptor) signaling, GTPase-activating proteins (GAPs) play a critical role in enhancing the GTPase activity of G-proteins. G-proteins are molecular switches that alternate between an active state (bound to GTP) and an inactive state (bound to GDP). The GTPase activity refers to the enzyme activity that hydrolyzes GTP to GDP, leading to the termination of the signaling response.

GAPs facilitate this process by promoting the hydrolysis of GTP, effectively speeding up the inactivation of the G-protein. This action is crucial for regulating how long and how strongly the signal is propagated following GPCR activation. Without the function of GAPs, the G-proteins would remain in their active state longer than necessary, which could lead to prolonged signaling and potential cellular dysfunction.

In summary, GAPs serve as important regulators that ensure the timely termination of signals in GPCR pathways by enhancing the natural GTPase activity of G-proteins. This modulation is vital for maintaining cellular responsiveness and appropriate signaling dynamics.