Question

Enzyme X catalyzes hydrolysis of GTP into GDP. The GTP-bound form of X transmits a signal that leads to cell proliferation. The GDP – bound form does not transmit any such signal. Mutations in X are found in many cancers. Which of the following alterations of X are most likely to contribute to cancer?

(A)  Mutations that increase the affinity of X for GDP 

(B)  Mutations that decrease the affinity of X for GTP 

(C)  Mutations that decrease the rate of GTP hydrolysis

(D)  Mutations that prevent expression of en zyme X. 

Answer 1

Correct option  (C) Mutations that decrease the rate of GTP hydrolysis

Explanation:

Mutation cause the decrease of rate of hydrolysis of GTP. Thus GTP –X complex remain present for long time and cell division become uncontrolled.