Neurotransmitter gated channels - relating structure to function
The 5-HT3 receptor is a member of the family of neurotransmitter gated ion channels that includes nicotinic acetylcholine, GABA and glycine receptors. These proteins are pentameric, but the 5-HT3 receptor is unusual in that can function with five identical subunits, thus allowing better interpretation of structural data. As yet there are no X-ray crystal structures of these proteins available, and therefore we are examining the roles of particular residues and protein motifs which may be important for structure and function. A range of different projects are available, all of which are multidisciplinary and involve molecular biology, protein chemistry and functional assays.
The aim of one project, for example, is to examine which proline residues are critical for forming the correct structure of the neurotransmitter binding site. You will do this using site-directed mutagenesis to change each proline residue to alanine and then examine the effect of these changes on radioligand binding characteristics, function as assessed using electrophysiology and calcium imaging techniques, and localization of the receptor using immunocytochemistry.
D.C. Reeves, M.F.R. Sayed, P.-L. Chau, K.L. Price and S.C.R. Lummis (2003) Prediction of 5-HT3 receptor agonist-binding residues using homology modelling, Biophysical Journal,;84:2338-4..
Spier AD & Lummis, SCR (2000) The role of tryptophan residues in the 5-hydroxytryptamine3 receptor ligand binding domain. J Biol Chem, 275, 2650-5
Reeves, D.C., Goren, E.N., Akabas, M.H. & Lummis, S.C.R. (2001) Structural and electrostatic properties of the 5-HT3 receptor pore revealed by substituted cysteine accessibility mutagenesis. J. Biol Chem. 276, 42035-42042.