Question

The Ras protein functions as a molecular switch that is set to its "on" state by other proteins that cause it to expel its bound GDP and bind GTP. A GTPase-activating protein helps reset the switch to the "off" state by inducing Ras to hydrolyze its bound GTP to GDP much more rapidly than it would without this encouragement. Thus, Ras works like a light switch that one person turns on and another turns off. You are given a mutant cell that lacks the GTPase-activating protein. What abnormalities would you expect to find in the way in which Ras activity responds to extracellular signals?

Answer 1

Answer: Ras activity would be significantly slower in its response to extracellular signals.

Explanation:

• GTPase acts as a catalyst in converting RasGTP (active state) to RasGDP (inactive state)

• A mutant lacking the GTPase activating protein cannot activate GTPase so thee will nit be any functional GTPase

• if GTPase is not present then RasGTP may be expdessed for longer periods of time and there will be a lag until it eventually switches "off)