Activation of G Proteins by Guanine Nucleotide Exchange Factors Relies on GTPase Activity.

ABSTRACT: G proteins are an important family of signalling molecules controlled by guanine nucleotide exchange and GTPase activity in what is commonly called an 'activation/inactivation cycle'. The molecular mechanism by which guanine nucleotide exchange factors (GEFs) catalyse the activation of monomeric G proteins is well-established, however the complete reversibility of this mechanism is often overlooked. Here, we use a theoretical approach to prove that GEFs are unable to positively control G protein systems at steady-state in the absence of GTPase activity. Instead, positive regulation of G proteins must be seen as a product of the competition between guanine nucleotide exchange and GTPase activity--emphasising a central role for GTPase activity beyond merely signal termination. We conclude th

SUBMITTER: Stanley RJ 

PROVIDER: S-EPMC4795700 | biostudies-literature | 2016

REPOSITORIES: biostudies-literature