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You searched for +publisher:"University of Cambridge" +contributor:("Lummis, Sarah C.R"). One record found.

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University of Cambridge

1. McGonigle, Ian Vincent. Molecular pharmacology of an insect GABA receptor .

Degree: 2010, University of Cambridge

Cys-loop receptors are ligand-gated ion channels that are involved in fast synaptic neurotransmission in the central and peripheral nervous system. The Cys-loop receptor RDL (‘resistant to dieldrin’) is a GABA-gated chloride channel from Drosophila melanogaster and is a major target site for insecticides. The aim of this dissertation was to characterise RDL receptors with particular focus on the agonist binding site. To assess the potency of a range of GABA analogues on RDL receptors, I expressed receptors in Xenopus oocytes and used voltage-clamp electrophysiology to detect receptor responses. I carried out computational modelling of these analogues to determine the dipole separation distances and atomic charges. Computational calculations and functional experiments revealed that agonists require a charged ammonium and an anionic centre, with the most potent agonists having a dipole separation distance of ~5 Å. I made a homology model of the extracellular domain of RDL and docked the active analogues into the putative binding site. I then conducted mutagenesis studies to test the accuracy of this model. Functional data from mutagenesis studies broadly support the location of GABA within this model. This model may be useful for further structure−activity studies and rational drug design. Natural compounds from the traditional Chinese medicine ‘Ginkgo biloba’ (ginkgolide A, ginkgolide B and bilobalide) have potent insecticidal properties and are similar in structure to picrotoxin. I tested the effect of these compounds on RDL receptor function using voltage-clamp electrophysiology. All compounds were found to inhibit RDL receptor function. I probed the binding site of these compounds using site-directed mutagenesis and electrophysiology. Mutations to the 2'A and 6'T channel-lining (M2) residues greatly reduced the potency of these compounds. I then made a homology model of the transmembrane domain of RDL and docked these compounds into the channel. Compounds docked into the channel pore close to the 2' and 6' channel-lining residues and H-bonding interactions were detected at these locations. Ginkgolides are therefore antagonists of RDL receptors, binding in the channel close to the 2' and 6' residues and this may be the mechanism underlying their potent insecticidal properties. The 5-HT3 receptor is a member of the Cys-loop receptor family and shows homology to RDL receptors. To explore different techniques for studying Cys-loop receptor function I assessed the functionality of two brain derived transcripts of the 5-HT3B subunit (Br1 and Br2) using single-channel electrophysiology and a fluorometric assay. Receptors containing Br1 were found to have a conductance identical to the 5-HT3B subunit whilst Br2 receptors were found not to be expressed. This finding has implications for 5-HT3 brain signalling, in which Br1 may play an important role. In conclusion, work here has described how agonists bind to and activate RDL GABA receptors and I have identified a candidate mechanism for the potent insecticidal… Advisors/Committee Members: Lummis, Sarah C.R (advisor).

Subjects/Keywords: Cys-loop; GABA; Drosophila; Ginkgolide

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

McGonigle, I. V. (2010). Molecular pharmacology of an insect GABA receptor . (Thesis). University of Cambridge. Retrieved from http://www.dspace.cam.ac.uk/handle/1810/226857

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

McGonigle, Ian Vincent. “Molecular pharmacology of an insect GABA receptor .” 2010. Thesis, University of Cambridge. Accessed September 23, 2019. http://www.dspace.cam.ac.uk/handle/1810/226857.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

McGonigle, Ian Vincent. “Molecular pharmacology of an insect GABA receptor .” 2010. Web. 23 Sep 2019.

Vancouver:

McGonigle IV. Molecular pharmacology of an insect GABA receptor . [Internet] [Thesis]. University of Cambridge; 2010. [cited 2019 Sep 23]. Available from: http://www.dspace.cam.ac.uk/handle/1810/226857.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

McGonigle IV. Molecular pharmacology of an insect GABA receptor . [Thesis]. University of Cambridge; 2010. Available from: http://www.dspace.cam.ac.uk/handle/1810/226857

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

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