A G protein is
A) off when bound to GTP, on when bound to GDP
B) off when bound to GDP, on when bound to GTP
C) off when disassociated, on when bound to GDP
D) on when disassociated, off when bound to GTP

Question

Quizplus · Accepted Answer

G proteins are activated when they exchange GDP for GTP, causing a conformational change that allows them to interact with other signaling molecules. Once the G protein has carried out its signaling function, it hydrolyzes GTP to GDP and returns to its inactive state. Therefore, G proteins are off when bound to GDP and on when bound to GTP.

A G Protein Is