English
 
Help Privacy Policy Disclaimer
  Advanced SearchBrowse

Item

ITEM ACTIONS
  This item is discarded!DetailsSummary

Discarded

Journal Article

Ligand binding sites and subunit interactions of Torpedo californica acetylcholine receptor

MPS-Authors
/persons/resource/persons95970

Witzemann,  Veit
Department of Molecular Neurobiology, Max Planck Institute for Medical Research, Max Planck Society;
Working Group Witzemann / Koenen, Max Planck Institute for Medical Research, Max Planck Society;
Molecular anatomy of the neuromuscular junction, Max Planck Institute for Medical Research, Max Planck Society;
Department of Cell Physiology, Max Planck Institute for Medical Research, Max Planck Society;

External Resource
No external resources are shared
Fulltext (restricted access)
There are currently no full texts shared for your IP range.
Fulltext (public)
There are no public fulltexts stored in PuRe
Supplementary Material (public)
There is no public supplementary material available
Citation

Witzemann, V., & Raftery, M. A. (1978). Ligand binding sites and subunit interactions of Torpedo californica acetylcholine receptor. Biochemistry, 17(17), 3598-3604. doi:10.1021/bi00610a028.


Abstract
A [3H]bisazido derivative of ethidium bromide was synthesized to identify sites of interaction of ethidium with the acetylcholine receptor from Torpedo californica and to aid in localization of ligand binding sites. For purified solubilized acetylcholine receptor it was shown (a) that the photolabel was competitive with ethidium bromide, (b) dodecyl sulfate−−polyacrylamide gel electrophoresis revealed that all four polypeptide components were labeled with [3H]ethidium azide, and (c) alpha−bungarotoxin inhibited the labeling of the 40 000−dalton subunit. Photolabeling of acetylcholine−−receptor enriched membrane fragments led to the following conclusions: (a) the photochemical reaction was more selective than for purified acetylcholine receptor, since the 40 000−dalton subunit was preferentially labeled; this result demonstrated differences in the topography of receptor subunits depending on whether the molecule was in detergent solution or in a membrane−bound state, (b) alpha−bungarotoxin inhibited labeling of the 40 000−dalton subunit, (c) ligand−induced conformational changes resulted in different subunit labeling patterns. The results imply that conformational changes generated at the 40 000 molecular weight subunit upon cholinergic ligand interaction cause further intermolecular structural changes that involve subunits of higher molecular weight. These higher molecular weight subunits therefore belong to a supramolecular complex of polypeptides associated with the postsynaptic membrane