The long-term objectives of this proposal are to identify the molecular mechanisms by which G protein-coupled receptors transduce signals into cells. This information will be important for understanding fundamental aspects of cell signaling, development, and disease mechanisms. Insights into how this important receptor superfamily works as ligand-activated switches will aid in drug design and greatly impact medicine more than half of currently prescribed pharmaceuticals target G protein-coupled receptors. The potential for new therapies acting on these receptors is great; an estimated 3 percent of the human genome encodes G protein-coupled receptors. Despite their widespread importance, we do not understand how the receptors actually function as ligand-activated switches. Recent evidence demonstrates that G protein-coupled receptors, such as adrenergic and dopamine receptors, form homodimers; the 8 and K-opiate receptors have been shown to form heterodimers with novel pharmacology. Little is known about if the receptors interact via specific dimer interfaces or larger oligomeric structures, the physiologic significance of receptor dimerization/oligomerization, and if this is a general mechanism for other G protein-coupled receptors. To address these fundamental questions, this proposal employs a variety of techniques including genetic studies, fluorescence energy transfer, biochemical crosslinking, and computer modeling. These studies will be performed on the human complement factor 5 (C5a) receptor, a chemoattractant receptor that mediates neutrophil chemotaxis. This receptor functions well when expressed in yeast, making possible high-throughput structure/function studies on the C5a receptor. In parallel studies in mammalian cells, the information gained from the genetic studies wifl be used to ask specific questions regarding receptor activation mechanisms and if dimerization / oligomerization plays a role in receptor function. These studies should add to our understanding of the receptor activation mechanisms for G protein signaling.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM063720-05
Application #
7108528
Study Section
Cell Development and Function Integrated Review Group (CDF)
Program Officer
Anderson, Richard A
Project Start
2002-04-01
Project End
2008-08-31
Budget Start
2006-09-01
Budget End
2008-08-31
Support Year
5
Fiscal Year
2006
Total Cost
$251,000
Indirect Cost
Name
Washington University
Department
Other Basic Sciences
Type
Schools of Medicine
DUNS #
068552207
City
Saint Louis
State
MO
Country
United States
Zip Code
63130
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Nikiforovich, Gregory V; Marshall, Garland R; Baranski, Thomas J (2011) Simplified modeling approach suggests structural mechanisms for constitutive activation of the C5a receptor. Proteins 79:787-802
Nikiforovich, Gregory V; Baranski, Thomas J (2010) Computational modeling of constitutively active mutants of GPCRs C5a receptor. Methods Enzymol 485:369-91
Nikiforovich, Gregory V; Taylor, Christina M; Marshall, Garland R et al. (2010) Modeling the possible conformations of the extracellular loops in G-protein-coupled receptors. Proteins 78:271-85
Van Eps, Ned; Anderson, Lori L; Kisselev, Oleg G et al. (2010) Electron paramagnetic resonance studies of functionally active, nitroxide spin-labeled peptide analogues of the C-terminus of a G-protein alpha subunit. Biochemistry 49:6877-86
Nikiforovich, Gregory V; Baranski, Thomas J (2009) Structural models for the complex of chemotaxis inhibitory protein of Staphylococcus aureus with the C5a receptor. Biochem Biophys Res Commun 390:481-4
Klco, Jeffery M; Sen, Saurabh; Hansen, Jakob L et al. (2009) Complement factor 5a receptor chimeras reveal the importance of lipid-facing residues in transport competence. FEBS J 276:2786-800
Nikiforovich, Gregory V; Marshall, Garland R; Baranski, Thomas J (2008) Modeling molecular mechanisms of binding of the anaphylatoxin C5a to the C5a receptor. Biochemistry 47:3117-30
Hagemann, Ian S; Miller, Daniel L; Klco, Jeffery M et al. (2008) Structure of the complement factor 5a receptor-ligand complex studied by disulfide trapping and molecular modeling. J Biol Chem 283:7763-75

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