Characterization of galanin receptors using chimeric peptides and site-directed mutagenesis
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Galanin, a 29 (30) amino acid neuropeptide, is found throughout both the central and peripheral nervous systems. It signals via three receptors, GalR1-3, all belonging to the rhodopsin-like G-protein coupled receptors. Galanin and its receptors have been implicated in a vast variety of biological processes. To facilitate further characterization of the physiological/pathological roles of galanin, subtype selective ligands targeting the three receptors individually would be of great aid.
In this thesis the main objective was to provide more information about galanin receptor-ligand interactions, primarily concerning GalR2 and 3. By using information gained from previously developed chimeric peptides, we designed and synthesized a novel peptide selective towards GalR2 (Paper I). This peptide, M871, binds GalR2 in an inhibitory manner, likely due to its truncated N-terminus and bulky character. In Paper II and IV we performed L-alanine mutagenesis assays of GalR2 and 3 respectively. By point substituting amino acid residues in the receptor sequence, we identified crucial pharmacophores for ligand binding, primarily in transmembrane regions 6 and 7. The targeted residues were selected based on knowledge concerning GalR1 and on conservation between the three receptors. For GalR3 we also conducted a computational docking assay. A homology model was first constructed using three crystallized structures of other receptors also belonging to the Rhodopsin family. Ligands galanin(2-6) and SNAP398299 were then docked to GalR3 in flexible mode. The docking resulted in characterization of GalR3-ligand interactions and conclude that this receptor display a relatively deep and narrow binding pocket. As a result of this, it was hypothesized that the C-terminus of ligands is of importance for GalR3 affinity. An L-alanine scan of ligand was performed (paper III), which confirmed this theory.
In conclusion, our results give insights into galanin receptor-ligand interactions, information that is relevant for ligand design and drug development.
Place, publisher, year, edition, pages
Stockholm: Department of Neurochemistry, Stockholm University , 2010. , 70 p.
galanin, GPCR, mutagenesis, neuropeptide
Research subject Neurochemistry and Neurotoxicology
IdentifiersURN: urn:nbn:se:su:diva-37259ISBN: 978-91-7447-018-5OAI: oai:DiVA.org:su-37259DiVA: diva2:297887
2010-04-23, Magnélisalen, Kemiska övningslaboratoriet, Svante Arrhenius väg 16 B, Stockholm, 10:00 (English)
Hulting, Anna-Lena, Professor
Langel, Ülo, Professor
At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 4: Manuscript.2010-03-292010-02-182015-04-21Bibliographically approved
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