The protein SOS is a guanine nucleotide exchange factor for Ras.SOS helps facilitate the exchange of GDP for GTP.What would be the effect of a mutation that inhibits the interaction between SOS and Ras?
A)GTP would remain bound to Ras,thereby disrupting downstream signaling events.
B)GDP would remain bound to Ras,thereby disrupting downstream signaling events.
C)GTP would remain bound to Ras,leading to overstimulation of the Ras pathway.
D)GDP would remain bound to Ras,leading to overstimulation of the Ras pathway.

Question

Quizplus · Accepted Answer

The mutation that inhibits the interaction between SOS and Ras would prevent the exchange of GDP for GTP. Therefore, GDP would remain bound to Ras, inhibiting downstream signaling events. This would disrupt the Ras pathway rather than overstimulating it. Choice A and C are incorrect because they describe the opposite effect of the mutation. Choice D is incorrect because it suggests that GDP-bound Ras would overstimulate the pathway, which is not the case.

The Protein SOS Is a Guanine Nucleotide Exchange Factor for Ras.SOS