Question

How does the GTP-bound form of a GTP-binding protein switch to a GDP-bound
form?

Answer 1

When a signaling molecule binds to the G-protein-coupled receptor, the G protein a subunit exchanges GTP for GDP. This exchange is facilitated by the activation of a guanine nucleotide exchange factor (GEF) and the hydrolysis of GTP to GDP inactivates the G protein.

Step-by-step explanation:

When a signaling molecule binds to the G-protein-coupled receptor, the G protein a subunit exchanges GTP for GDP. This exchange is facilitated by the activation of a guanine nucleotide exchange factor (GEF), which promotes the release of GDP and the binding of GTP to the G protein a subunit. Once GTP is bound, the G protein a subunit becomes activated and initiates downstream signaling events. However, the GTP-bound form is eventually hydrolyzed to GDP by the intrinsic GTPase activity of the G protein a subunit, resulting in the inactivation of the G protein.