Question

what would be the consequence of a mutation in G(alpha) where it lowers is affinity for GDP but does not change its affinty fir GTP?

Answer 1

In case of a mutation in the G alpha subunit that remains bound to GTP and does not bind to GDP, the G proteins remain constitutively active and the downstream molecules perform their function continuously. As it remains in an active form, no ligand is required to activate this signaling, and even when not required this signaling process goes on thus bringing adverse effects on the cells. The switch on, switch off system is lost and it remains in the on condition always.