Rings of anionic amino acids as structural determinants of ion selectivity in the acetylcholine receptor channel

T. Konno, C. Busch, K. Imoto, E. Von Kitzing, F. Wang, J. Nakai, M. Mishina, S. Numa, B. Sakmann

Research output: Contribution to journalArticlepeer-review

110 Citations (Scopus)

Abstract

To gain an insight into the molecular basis of the weak but significant selectivity among alkali metal cations of the nicotinic acetylcholine receptor (AChR) channel, we have determined single-channel conductance and permeability ratios for alkali metal cations on specifically mutated Torpedo californica AChR channels expressed in Xenopus oocytes. The mutations involved charged and polar side chains in the three anionic rings (extracellular, intermediate and cytoplasmic ring) which have previously been found to determine the rate of K+ transport through the AChR channel. The results obtained reveal that mutations in the intermediate ring exert much stronger effects on ion selectivity than do mutations in the extracellular and the cytoplasmic ring. The experimental results, together with simulations of the channel's energy profile, suggest that the amino acid residues forming the intermediate ring come into close contact with permeating cations and possibly represent part of the physical correlate of the postulated selectivity filter in the AChR channel.

Original languageEnglish
Pages (from-to)69-79
Number of pages11
JournalProceedings of the Royal Society B: Biological Sciences
Volume244
Issue number1310
DOIs
Publication statusPublished - 1991

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Immunology and Microbiology(all)
  • Environmental Science(all)
  • Agricultural and Biological Sciences(all)

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