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Updated: Mar 11, 2026

Strategic Screening and Characterization of the Visual GPCR-mini-G Protein Signaling Complex for Successful Crystallization
Published on: March 16, 2020
Crystal structure of cGMP-dependent protein kinase Iβ cyclic nucleotide-binding-B domain : Rp-cGMPS complex reveals
James C Campbell1,2, Bryan VanSchouwen3, Robin Lorenz4
1Structural and Computational Biology and Molecular Biophysics Program, Baylor College of Medicine, Houston, TX, USA.
Abstract:
The R-diastereomer of phosphorothioate analogs of cGMP, Rp-cGMPS, is one of few known inhibitors of cGMP-dependent protein kinase I (PKG I); however, its mechanism of inhibition is currently not fully understood. Here, we determined the crystal structure of the PKG Iβ cyclic nucleotide-binding domain (PKG Iβ CNB-B), considered a 'gatekeeper' for cGMP activation, bound to Rp-cGMPS at 1.3 Å. Our structural and NMR data show that PKG Iβ CNB-B bound to Rp-cGMPS displays an apo-like structure with its helical domain in an open conformation. Comparison with the cAMP-dependent protein kinase regulatory subunit (PKA RIα) showed that this conformation resembles the catalytic subunit-bound inhibited state of PKA RIα more closely than the apo or Rp-cAMPS-bound conformations. These results suggest that Rp-cGMPS inhibits PKG I by stabilizing the inactive conformation of CNB-B.
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