CDC42 Activity: Upregulated by Constitutive GAP Activation?

[Alt+F4]

Consider a cell in which you have driven the expression of a constitutively active GTPase Activating Protein (GAP) for CDC42, an important Rho-family GTPase. In these cells, CDC42's activity would most likely be:

A.Downregulated because activating the GTPase function of CDC42 causes it to be associated with GDP, in which state CDC42 is inactive.
B.Downregulated because the association of CDC42 with a constitutively active GAP will cause CDC42 to be degraded.
C.Upregulated because a GAP activates the GTPase it works with.
D.Unaffected because the association of CDC42 with a constitutively active GAP will cause CDC42 to be degraded.
E. Upregulated because constitutive activation of any protein will induce a heat-shock response by the cell inducing it to transcribe many genes as quickly as it can.


I am going towards C, i know it will not be downregulated since there is GTP Avaliable. E just makes no sense so i can get rid of it. So i am left with C and D but I am leing towards C

 

[nate808]

because GAPs are known to activate GTPases. This means that the activity of CDC42 would most likely be upregulated in this scenario. The GAP would enhance the GTPase function of CDC42, leading to an increase in its activity. This could potentially have a significant effect on cellular processes that are regulated by CDC42, such as cell migration, cell cycle progression, and cytoskeletal organization. Additionally, the constitutive activation of CDC42 could potentially have a negative effect on the cell, as it may lead to excessive signaling and disruption of normal cellular processes. Therefore, careful regulation of CDC42 activity through the use of a constitutively active GAP would be important in maintaining cellular homeostasis. In conclusion, the most likely outcome in this scenario would be an upregulation of CDC42 activity due to the constitutive activation of a GAP for CDC42.

 

[Blueshift5]

because GAP usually activates GTPase.

Correct. The correct answer is C. Upregulated because a GAP activates the GTPase it works with. Constitutive activation of the GAP will lead to increased activation of CDC42, as the GAP activates the GTPase function of CDC42. This will result in an upregulation of CDC42 activity in the cell. Option D, stating that CDC42 will be unaffected because it will be degraded, is incorrect as the constitutively active GAP will lead to increased activation of CDC42, not degradation. Option E, stating that constitutive activation of any protein will induce a heat-shock response, is incorrect as this response is not directly related to the activity of CDC42.