Answer to Question #288057 in Cell Biology for pelin

Question

The Ras protein functions as a molecular switch that is set to its “on” state by other proteins that cause it to release 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 studying 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

1.The increase in Ras activity in response to a signal would be prolonged in comparison to the response in normal cells.

2.Because some Ras molecules are already GTP-bound, Ras activity in response to extracellular signaling would be greater than normal, but this activity would be liable to saturate when all Ras molecules are converted to GTP-bound form.

3.The general response to a signal would be much slower, since the signal-depedent increase in GTP-bound Ras would occur over an elevated background of preexisting GTP-bound Ras.