Summarize the steps in the cycling of GTPase switch proteins

Summarize the steps in the cycling of GTPase switch proteins from active to inactive states.

Solution

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Changing the switch of the GTPase switch proteins is performed by the unidirectional change of the GTPase from the active, GTP-bound form to the inactive, GDP-bound form by hydrolysis of the GTP through intrinsic GTPase-activity, effectively switching the GTPase off

This reaction is initiated by GTPase-activating proteins (GAPs), coming from another signal transduction pathway.

It can be reversed (switching the GTPase on again) by Guanine nucleotide exchange factors (GEFs), which cause the GDP to dissociate from the GTPase, leading to its association with a new GTP.

This closes the cycle to the active state of the GTPase; the irreversible hydrolysis of the GTP to GDP forces the cycle to run only in one direction.

Only the active state of the GTPase can transduce a signal to a reaction chain.

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