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Updated: Jul 27, 2026

Comparing the Affinity of GTPase-binding Proteins using Competition Assays
Published on: October 8, 2015
Conformational display: a role for switch polymorphism in the superfamily of regulatory GTPases
1Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX, USA. sprang@chop.swmed.edu
Abstract:
Regulating signal transduction is serious business. If signals are improperly controlled, aberrant proliferation or inappropriate cell death may result. The Ras superfamily of small guanosine triphosphatases (GTPases) and the heterotrimeric G proteins require GTP binding into their active sites for subsequent activation. Hydrolysis of GTP to GDP precedes, and is a requirement for, inactivation. However, the changes in conformation that accompany GTP or GDP binding are now becoming fully appreciated. Sprang discusses the importance of conformation in the activation of GTPases and heterotrimeric G proteins, and the possibility that these proteins exist in several different conformations. Thus, rather than a simplistic on/off two-conformation model, these signaling proteins exist in several differing conformations that may be related to activation and effector protein binding.
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