Int. J. Mol. Sci. 2013, 14(2), 2788-2807; doi:10.3390/ijms14022788
Article

Structural Characterization of an LPA1 Second Extracellular Loop Mimetic with a Self-Assembling Coiled-Coil Folding Constraint

Received: 11 October 2012; in revised form: 16 November 2012 / Accepted: 24 January 2013 / Published: 29 January 2013
(This article belongs to the Special Issue Phospholipids: Molecular Sciences 2012)
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract: G protein-coupled receptor (GPCR) structures are of interest as a means to understand biological signal transduction and as tools for therapeutic discovery. The growing number of GPCR crystal structures demonstrates that the extracellular loops (EL) connecting the membrane-spanning helices show tremendous structural variability relative to the more structurally-conserved seven transmembrane α-helical domains. The EL of the LPA1 receptor have not yet been conclusively resolved, and bear limited sequence identity to known structures. This study involved development of a peptide to characterize the intrinsic structure of the LPA1 GPCR second EL. The loop was embedded between two helices that assemble into a coiled-coil, which served as a receptor-mimetic folding constraint (LPA1-CC-EL2 peptide). The ensemble of structures from multi-dimensional NMR experiments demonstrated that a robust coiled-coil formed without noticeable deformation due to the EL2 sequence. In contrast, the EL2 sequence showed well-defined structure only near its C-terminal residues. The NMR ensemble was combined with a computational model of the LPA1 receptor that had previously been validated. The resulting hybrid models were evaluated using docking. Nine different hybrid models interacted with LPA 18:1 as expected, based on prior mutagenesis studies, and one was additionally consistent with antagonist affinity trends.
Keywords: G protein-coupled receptor; GPCR; lysophosphatidic acid; LPA; NMR; GPCR segment model
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MDPI and ACS Style

Young, J.K.; Clayton, B.T.; Kikonyogo, A.; Pham, T.-C.T.; Parrill, A.L. Structural Characterization of an LPA1 Second Extracellular Loop Mimetic with a Self-Assembling Coiled-Coil Folding Constraint. Int. J. Mol. Sci. 2013, 14, 2788-2807.

AMA Style

Young JK, Clayton BT, Kikonyogo A, Pham T-CT, Parrill AL. Structural Characterization of an LPA1 Second Extracellular Loop Mimetic with a Self-Assembling Coiled-Coil Folding Constraint. International Journal of Molecular Sciences. 2013; 14(2):2788-2807.

Chicago/Turabian Style

Young, John K.; Clayton, Benjamin T.; Kikonyogo, Alexandra; Pham, Truc-Chi T.; Parrill, Abby L. 2013. "Structural Characterization of an LPA1 Second Extracellular Loop Mimetic with a Self-Assembling Coiled-Coil Folding Constraint." Int. J. Mol. Sci. 14, no. 2: 2788-2807.

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