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Updated: Jul 19, 2026

Strategic Screening and Characterization of the Visual GPCR-mini-G Protein Signaling Complex for Successful Crystallization
Published on: March 16, 2020
Rhodopsin-transducin coupling: role of the Galpha C-terminus in nucleotide exchange catalysis
Rolf Herrmann1, Martin Heck, Peter Henklein
1Institut für medizinische Physik und Biophysik (CCM), Charité-Universitätsmedizin Berlin, Schumannstr. 20/21, 10098 Berlin, Germany. rolf.herrmann@duke.edu
Abstract:
In the early steps of visual signal transduction, light-activated rhodopsin (R*) catalyzes GDP/GTP exchange in the heterotrimeric G protein (Galphabetagamma) transducin. We recently reported that the catalytic interaction involves two sequential steps. An initial docking between R* and Gbetagamma leads to conformational changes which make the C-terminus of Galpha (CTalpha) available for binding to R*. Binding of CTalpha by R* then triggers GDP/GTP exchange in the Galpha subunit. To further study this two-step mechanism, we investigated different single amino acid substitutions within CTalpha and discuss the effects of high affinity mutations on nucleotide exchange catalysis.
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