Enzyme X catalyses 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?

Question

Enzyme X catalyses 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 enzyme X

Tardigrade Admin · Accepted Answer

GTP-X complex arrow Active cell division GDP-X-complex arrow No cell division and GTP ->[ texthydrolysis][ textX-enzyme] GDP Mutation causes the decrease of rate of hydrolysis of GTP. Thus, GTP-X complex remains present for long time and cell division becomes uncontrolled.

Mutations that increase the affinity of X for GDP

Mutations that decrease the affinity of X for GTP

Mutations that decrease the rate of GTP hydrolysis

Mutations that prevent expression of enzyme X

GTP-X complex → Active cell division GDP-X-complex → No cell division and GTP hydrolysisX-enzyme​GDP Mutation causes the decrease of rate of hydrolysis of GTP. Thus, GTP-X complex remains present for long time and cell division becomes uncontrolled.

GTP-X complex $\to$ Active cell division
GDP-X-complex $\to$ No cell division
and GTP $hydrolysis X-enzyme GDP$
Mutation causes the decrease of rate of hydrolysis of GTP. Thus, GTP-X complex remains present for long time and cell division becomes uncontrolled.