Stable expression and pharmacological properties of the human alpha 7 nicotinic acetylcholine receptor

Eur J Pharmacol. 1995 Aug 15;290(3):237-46. doi: 10.1016/0922-4106(95)00083-6.


The alpha 7 neuronal nicotinic acetylcholine receptor subtype forms a Ca(2+)-permeable homooligomeric ion channel sensitive to alpha-bungarotoxin in Xenopus oocytes. In this study, we have stably and functionally expressed the human alpha 7 cDNA in a mammalian cell line, HEK-293 and examined its pharmacologic properties. [125I] alpha-Bungarotoxin bound to transfected cells with a Kd value of 0.7 nM and a Bmax value of 973 pmoL/mg protein. No specific binding was detected in untransfected cells. Specific binding could be displaced by unlabeled alpha-bungarotoxin (Ki = 0.5 nM) and an excellent correlation was observed between binding affinities of a series of nicotinic cholinergic ligands in transfected cells and those in the human neuroblastoma IMR-32 cell line. Additionally, cell surface expression of alpha 7 receptors was detected by fluorescein isothiocyanate-conjugated alpha-bungarotoxin in transfected cells. Whole cell currents sensitive to blockade by alpha-bungarotoxin, and with fast kinetics of activation and inactivation, were recorded from transfected cells upon rapid application of (-)-nicotine or acetylcholine with EC50 values of 49 microM and 155 microM respectively. We conclude that the human alpha 7 subunit when expressed alone can form functional ion channels and that the stably transfected HEK-293 cell line serves as a unique system for studying human alpha 7 nicotinic receptor function and regulation, and for examining ligand interactions.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acetylcholine / metabolism
  • Base Sequence
  • Bungarotoxins / pharmacology
  • Cell Line
  • Electrophysiology
  • Humans
  • Ion Channel Gating / physiology
  • Kidney / cytology
  • Kidney / metabolism
  • Kinetics
  • Molecular Sequence Data
  • Nicotine / metabolism
  • Nicotinic Antagonists / pharmacology
  • Patch-Clamp Techniques
  • RNA / metabolism
  • Receptors, Nicotinic / biosynthesis*
  • Receptors, Nicotinic / drug effects*
  • Recombinant Proteins / biosynthesis
  • Recombinant Proteins / metabolism
  • Transfection


  • Bungarotoxins
  • Nicotinic Antagonists
  • Receptors, Nicotinic
  • Recombinant Proteins
  • RNA
  • Nicotine
  • Acetylcholine