Cholinergic elements in a human choriocarcinoma cell line

Michael Fant, Kermit V. Speeg, Sandra Harper, Raymond D. Harbison

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


Components of the cholinergic system have been identified in the JEG choriocarcinoma cell line. [3H]Quinuclidinyl benzilate (QNB) was used to identify high affinity muscarinic binding sites in a whole cell preparation. Specific binding was saturable with respect to QNB concentration and revealed a binding site density of 27 fmoles/mg protein. The bimolecular rates of association, 2.24 × 107 M-1 min-1, and dissociation, 4.2 × 10-3min-1, revealed a dissociation constant (Kd) of 180 pM which agreed closely with that derived from saturation isotherms, 245 pM. Muscarinic antagonists and agonists were able to compete effectively for these binding sites, whereas non-muscarinic compounds were not. Cholinesterase activity was also demonstrated with substrate preference consistent with that of acetyl-cholinesterase (acetylcholine > acetyl-β-methylcholine > butyrylcholine) hydrolyzing 2.42 ± 0.19 × 10-3 μmoles acetylcholine·min-1 ·(mg protein)-1. No choline acetyltransferase activity was detected in these cells, however.

Original languageEnglish (US)
Pages (from-to)967-970
Number of pages4
JournalBiochemical Pharmacology
Issue number9
StatePublished - May 1 1981
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry
  • Pharmacology


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