Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2002 Oct;11(10):2526-31.
doi: 10.1110/ps.0218402.

Cannabinoid receptor-G protein interactions: G(alphai1)-bound structures of IC3 and a mutant with altered G protein specificity

Amy L Ulfers  1 , Jonathan L McMurry, Alexander Miller, Ligong Wang, Debra A Kendall, Dale F Mierke
Affiliations

Cannabinoid receptor-G protein interactions: G(alphai1)-bound structures of IC3 and a mutant with altered G protein specificity

Amy L Ulfers et al. Protein Sci. 2002 Oct.

Abstract

The structure of the C-terminal region of the third cytoplasmic loop (IC3) of the cannabinoid receptor one (CB1) bound to G(alphai1) has been determined using transferred nuclear Overhauser effects (NOEs). The wild-type IC3 sequence is helical when associated with G(alphai1). In contrast, a peptide containing the amino-acid inversion, Ala(341)-Leu(342) adopts a single turn. These findings correlate with the attenuated G(i) association of CB1 with the Ala(341)-Leu(342) mutation previously observed in vivo and the diminished stimulation of G(alphai1) GTPase activity by the corresponding peptide demonstrated in vitro here. These results, the first to report the structure of a GPCR domain while associated with G protein, imply the C-terminus of CB1 IC3, a region with high-sequence conservation among G-protein coupled receptors, must be helical for efficient coupling and activation of the G(i) protein.

PubMed Disclaimer

Figures

Fig. 1.
Fig. 1.
GTPase activity of Gαi1. The enzyme assays were conducted as described in Materials and Methods. Each data point represents an average of triplicate assays +/− SE. (A) Gαi1 GTPase activity in the absence and presence of 1 mM peptides and 200 μM GTP. (B) The dependence of Gαi1 GTPase activity on the concentration of the wild-type IC3 peptide (filled circles) and the Ala341-Leu342 variant (open circles). (C) The dependence of the peptide-stimulated Gαi1 GTPase activity on GTP concentration. The concentration of the wild-type IC3 peptide (filled circles) and the Ala341-Leu342 variant (open circles) was 1 mM.
Fig. 2.
Fig. 2.
Superposition of the ensemble of 20 structures from the DG calculations: (a) WT-IC3 and (b) AL-IC3. The heavy backbone atoms were used in the superposition.
Fig. 3.
Fig. 3.
Structure of (a) WT-IC3 and (b) AL-IC3 after IRMA refinement. The Connolly surface representation of the molecules are shown color coded by hydrophobicity (red represents hydrophobic, blue represents hydrophilic).
See this image and copyright information in PMC

References

    1. Abadji, V., Lucas-Lenard, J.M., Chin, C., and Kendall, D.A. 1999. Involvement of the carboxyl terminus of the third intracellular loop of the cannabinoid CB1 receptor in constitutive activation of Gs. J. Neurochem. 72 2032–2038. - PubMed
    1. Baker, D., Pryce, G., Croxford, J.L., Brown, P., Pertwee, R.G., Huffman, J.W., and Layward, L. 2000. Cannabinoids control spasticity and tremor in a multiple sclerosis model. Nature 404 84–87. - PubMed
    1. Boelens, R., Koning, T.M.G., van der Marel, G.A., Van Boom, H., and Kaptein, R. 1989. Iterative procedure for structure determination from proton-proton NOEs using a relaxation matrix approach, application to a DNA octamer. J. Magn. Reson. 82 290.
    1. Bonvin, A.M., Rullmann, J.A., Lamerichs, R.M., Boelens, R., and Kaptein, R. 1993. "Ensemble" iterative relaxation matrix approach: A new NMR refinement protocol applied to the solution structure of crambin. Proteins 15 385–400. - PubMed
    1. Cotecchia, S., Exum, S., Caron, M.G., and Lefkowitz, R.J. 1990. Regions of the α 1-adrenergic receptor involved in coupling to phosphatidylinositol hydrolysis and enhanced sensitivity of biological function. Proc. Natl. Acad. Sci. 87 2896–2900. - PMC - PubMed

MeSH terms

LinkOut - more resources