Analysis of exposed regions on the main extracellular domain of mouse acetylcholine receptor α subunit in live muscle cells by binding profiles of antipeptide antibodies

Kenji Jinnai, Tetsuo Ashizawa, M. Zouhair Atassi

Research output: Contribution to journalArticle

3 Scopus citations

Abstract

To study the structural organization of the main extracellular domain of the nicotinic acetylcholine receptor (AChR)α subunit in live muscle cells, we examined the native membrane-bound receptors in cultured mouse skeletal muscle cells for their ability to bind a panel of antibodies against uniform-sized overlapping synthetic peptides which collectively represent this entire domain. The binding profile indicated that the regions α23-49, α78-126, α146-174, and α182-210 are accessible to binding with antibody. Residues α23-49, α78-126, and α194-210 contain binding regions for α-neurotoxin and some myasthenia gravis autoantibodies. A comparison of this binding profile with the profile obtained for membrane-bound Torpedo californica AChR in isolated membrane fractions showed some similarities as well as significant differences between the subunit organization in the isolated membrane fraction and that in the membrane of live muscle cells. Regions α89-104 and α158-174, which are exposed in the isolated membrane fraction, are also exposed in the live cell. On the other hand, regions α23-49, and α182-210, which are exposed in the live cell, are not accessible in the isolated membrane and, furthermore, the region α1-16, which has marginal accessibility in the cell, becomes highly accessible in the membrane isolates. The exposed regions defined by this study may be the primary targets for the initial autoimmune attack on the receptors in experimental autoimmune myasthenia gravis.

Original languageEnglish (US)
Pages (from-to)715-722
Number of pages8
JournalJournal of Protein Chemistry
Volume13
Issue number8
DOIs
StatePublished - Nov 1994

Keywords

  • Antibody
  • acetylcholine receptor
  • binding profile
  • exposed regions
  • synthetic peptide

ASJC Scopus subject areas

  • Biochemistry

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