Patch clamp techniques will be used to study the gating mechanism of the acetylcholine receptor channel in cultured embryonic muscle. Many of the experiments will involve chemical modifications of the receptor in which a labile disulfide near the binding site is exploited to block ligand binding selectively. Studies of spontaneous acetylcholine receptor channel gating have shown that Alpha-bungarotoxin blocks the closed-to-open conformational transition of the channel, but a chemical modification of the binding sites does not. Chemical modification of a single binding site will therefore be used to produce receptors blocked at a single binding site, and see how they respond to ligand. Other experiments will exploit chemical reagents that are directed against the ion channel functionality of the receptor. Since local anesthetics bind to open channels, they should more frequently enter channels that stay open longer. The local anesthetic derivative quinacrine mustard, which binds covalently to the open channel, should preferentially inactivate channels that have a higher probability of being open. An irreversible channel blocker of this type could then be used to identify populations of channels that differ with regard to how much time they are open. Subconductance states were seen with ligand activated channels, but not spontaneous openings of the acetylcholine receptor channel. Recordings of channel currents following blockade of the binding site will determine if a cholinergic ligand can produce a transition to a subconductance state by binding to a site other than the sites responsible for receptor activation. A final program of experiments explores enzymatic modification of the acetylcholine receptor. The acetylcholine receptor is a phosphoprotein and is a substrate for many protein kinases. Channel gating will be examined following treatment with enzymes that change the state of phosphorylation.

National Institute of Health (NIH)
National Institute of Neurological Disorders and Stroke (NINDS)
Research Project (R01)
Project #
Application #
Study Section
Neurological Sciences Subcommittee 1 (NLS)
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
University of California Los Angeles
Schools of Arts and Sciences
Los Angeles
United States
Zip Code
Wang, C T; Zhang, H G; Rocheleau, T A et al. (1999) Cation permeability and cation-anion interactions in a mutant GABA-gated chloride channel from Drosophila. Biophys J 77:691-700
Jackson, M B (1997) Inversion of Markov processes to determine rate constants from single-channel data. Biophys J 73:1382-94
Zhang, H G; Lee, H J; Rocheleau, T et al. (1995) Subunit composition determines picrotoxin and bicuculline sensitivity of Drosophila gamma-aminobutyric acid receptors. Mol Pharmacol 48:835-40
Jackson, M B; Yakel, J L (1995) The 5-HT3 receptor channel. Annu Rev Physiol 57:447-68
Jackson, M B (1994) Single channel currents in the nicotinic acetylcholine receptor: a direct demonstration of allosteric transitions. Trends Biochem Sci 19:396-9
Zhang, H G; ffrench-Constant, R H; Jackson, M B (1994) A unique amino acid of the Drosophila GABA receptor with influence on drug sensitivity by two mechanisms. J Physiol 479 ( Pt 1):65-75
Jackson, M B (1992) Cable analysis with the whole-cell patch clamp. Theory and experiment. Biophys J 61:756-66
Shao, X M; Yakel, J L; Jackson, M B (1991) Differentiation of NG108-15 cells alters channel conductance and desensitization kinetics of the 5-HT3 receptor. J Neurophysiol 65:630-8
Yakel, J L; Shao, X M; Jackson, M B (1991) Activation and desensitization of the 5-HT3 receptor in a rat glioma x mouse neuroblastoma hybrid cell. J Physiol 436:293-308
Yakel, J L; Shao, X M; Jackson, M B (1990) The selectivity of the channel coupled to the 5-HT3 receptor. Brain Res 533:46-52

Showing the most recent 10 out of 12 publications