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SIGNAL TRANSDUCTION. Structural basis for nucleotide exchange in heterotrimeric G proteins. Science 2015 Jun 19;348(6241):1361-5 PMID: 26089515 PMCID: PMC4968074


G protein-coupled receptors (GPCRs) relay diverse extracellular signals into cells by catalyzing nucleotide release from heterotrimeric G proteins, but the mechanism underlying this quintessential molecular signaling event has remained unclear. Here we use atomic-level simulations to elucidate the nucleotide-release mechanism. We find that the G protein α subunit Ras and helical domains-previously observed to separate widely upon receptor binding to expose the nucleotide-binding site-separate spontaneously and frequently even in the absence of a receptor. Domain separation is necessary but not sufficient for rapid nucleotide release. Rather, receptors catalyze nucleotide release by favoring an internal structural rearrangement of the Ras domain that weakens its nucleotide affinity. We use double electron-electron resonance spectroscopy and protein engineering to confirm predictions of our computationally determined mechanism.

Author List

Dror RO, Mildorf TJ, Hilger D, Manglik A, Borhani DW, Arlow DH, Philippsen A, Villanueva N, Yang Z, Lerch MT, Hubbell WL, Kobilka BK, Sunahara RK, Shaw DE


Michael Lerch PhD Assistant Professor in the Biophysics department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

GTP-Binding Protein alpha Subunits, Gi-Go
GTP-Binding Protein alpha Subunits, Gs
Guanine Nucleotide Exchange Factors
Models, Chemical
Protein Structure, Secondary
Protein Structure, Tertiary
Receptors, G-Protein-Coupled
Signal Transduction

View this publication's entry at the Pubmed website PMID: 26089515
jenkins-FCD Prod-164 dfc08cb8c9ba6489ef52627ede450784778aa7cb