Multiple Determinants of Dihydro-Beta-Erythroidine Sensitivity on Rat Neuronal Nicotinic Receptor Alpha Subunits

J Neurochem. 1996 Nov;67(5):1953-9. doi: 10.1046/j.1471-4159.1996.67051953.x.

Abstract

Neuronal nicotinic acetylcholine receptors are differentially sensitive to blockade by the competitive antagonist dihydro-beta-erythroidine. Both alpha and beta subunits participate in determining sensitivity to this antagonist. The alpha subunit contribution to dihydro-beta-erythroidine sensitivity is illustrated by comparing the alpha 4 beta 4 receptor and the alpha 3 beta 4 receptor, which differ in sensitivity to dihydro-beta-erythroidine by approximately 120-fold. IC50 values for blocking alpha 4 beta 4 and alpha 3 beta 4, responding to EC20 concentrations of acetylcholine, were 0.19 +/- 0.06 and 23.1 +/- 10.2 microM, respectively. To map the sequence segments responsible for this difference, we constructed a series of chimeric alpha subunits containing portions of the alpha 4 and alpha 3 subunits. These chimeras were coexpressed with beta 4, allowing pharmacological characterization. We found determinants of dihydro-beta-erythroidine sensitivity to be distributed throughout the N-terminal extracellular domain of the alpha subunit. These determinants were localized to sequence segments 1-94, 94-152, and 195-215. Loss of determinants within segment 1-94 had the largest effect, decreasing dihydro-beta-erythroidine sensitivity by 4.3-fold.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Acetylcholine / pharmacology*
  • Animals
  • Dihydro-beta-Erythroidine / pharmacology*
  • Female
  • Macromolecular Substances
  • Membrane Potentials / drug effects
  • Neurons / physiology*
  • Oocytes / drug effects
  • Oocytes / physiology
  • Patch-Clamp Techniques
  • Rats
  • Receptors, Nicotinic / chemistry
  • Receptors, Nicotinic / drug effects
  • Receptors, Nicotinic / physiology*
  • Recombinant Fusion Proteins / chemistry
  • Recombinant Fusion Proteins / drug effects
  • Recombinant Fusion Proteins / metabolism
  • Xenopus laevis

Substances

  • Macromolecular Substances
  • Receptors, Nicotinic
  • Recombinant Fusion Proteins
  • Dihydro-beta-Erythroidine
  • Acetylcholine