4 YEAR PhD IN NEUROSCIENCE
Department of Neuroscience, Physiology & Pharmacology
Ion channels as single molecules
We work on channels in the nicotinic superfamily, in particular acetylcholine nicotinic receptors and glycine receptors, with the aim of understanding quantitatively how these channels function as single molecules. These receptors mediate fast synaptic transmission at the neuromuscular junction and in the central nervous system and respond to binding of the neurotransmitter to their extracellular domain by opening their transmembrane ion channel. We can follow this process by recording the single-channel currents: these data give us information about the different steps in the receptor activation. Advances in our analysis techniques have recently allowed us to identify an intermediate state in the activation of the receptor, which structurally may correspond to the closing of the binding domain on the transmitter molecule (see Lape et al., 2008). Quantitative modelling of the receptor in this way is useful for understanding synaptic currents and drug action on these channels.
Our special expertise is in single-channel recording and analysis and we use molecular biology to express wild-type or mutant receptors in Xenopus oocytes or mammalian cell lines and other electrophysiology techniques (two-electrode voltage clamp, and all configurations of patch clamp).
Ongoing projects include investigating new partial agonists on glycine receptors with single-channel recording (see also http://www.ucl.ac.uk/npp/ls.html); exploring new ways of “designing” receptor composition by expressing concatemeric constructs; examining the factors that affect the deactivation of currents mediated by glycine receptors (and therefore the time course of synaptic currents); identifying what residues transduct the signal from the binding site to the channel gate in glycine receptors.
Lape, Colquhoun & Sivilotti (2008)
On the nature of partial agonism in the nicotinic superfamily.
Nature 454, 722-727. See accompanying News & Views, Nature 454,704-5
Plested, Groot-Kormelink, Colquhoun & Sivilotti (2007)
Single channel study of the spasmodic mutation α1 A52S in recombinant rat glycine receptors.
J.Physiol, 581, 51-73. see accompanying Perspective, J.Physiol.. 581,3
Groot-Kormelink,, Broadbent, Beato &. Sivilotti (2006)
Constraining the expression of nicotinic acetylcholine receptors using pentameric constructs.
Mol. Pharm., 69, 558-63
Burzomato, Beato, Groot-Kormelink, Colquhoun & Sivilotti (2004)
Single-channel behavior of heteromeric α1 glycine receptors: An attempt to detect a conformational change before the channel opens
J.Neuroscience, 24, 10924-10940
Groot-Kormelink, Broadbent, Boorman &. Sivilotti (2004)
Incomplete incorporation of tandem subunits into recombinant neuronal nicotinic receptors.
J. Gen. Physiol. 123, 697-708
Colquhoun. & Sivilotti (2004)
Function and structure in glycine receptors and some of their relatives.
Trends Neurosci., 27, 337-344
Beato, Groot-Kormelink, Colquhoun & Sivilotti (2004)
The activation of α1 homomeric glycine receptors
J.Neuroscience, 24, 895-906