125I-labeled fasciculin 2: A new tool for quantitation of acetylcholinesterase densities at synaptic sites by EM-autoradiography

Lili Anglister*, Jerry Eichler, Maria Szabo, Brigitte Haesaert, Miriam M. Salpeter

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

26 Scopus citations


Radio-iodinated fasciculin 2 (Fas2), a polypeptide anticholinesterase toxin from Mamba venom, was used as a new probe for localizing and quantifying acetylcholinesterase (ACHE) at mouse neuromuscular junctions (NMJs) by quantitative electron microscope autoradiography. We demonstrate that 125I-Fas2 binds very specifically to the NMJs of mouse sternomastoid muscles, with very little binding to other regions in the muscles. Junctional AChE-site densities obtained from the autoradiograms were similar to those previously obtained for the same muscles using 3H-DFP. The use of 125I- Fas2 with EM-autoradiography is simpler and provides higher resolution and sensitivity, as well as considerably lower non-specific binding than previously attainable with 3H-DFP. The advantages and limitations of this procedure are discussed.

Original languageAmerican English
Pages (from-to)63-71
Number of pages9
JournalJournal of Neuroscience Methods
Issue number1-2
StatePublished - 1 Jun 1998

Bibliographical note

Funding Information:
This research was supported by grants from the Israel Academy of Sciences—Charles H. Revson Foundation 675/94 (to L. Anglister) and from NIH GM 10422 (to M.M. Salpeter). A preliminary account of the potential use of fasciculin for quantitative EM-autoradiography of AChE was presented in Anglister et al., In: Quinn DM et al., editors. Enzymes of the Cholinesterase Family. Plenum, 1995:277–285.


  • Acetylcholinesterase site density
  • EM-autoradiography
  • Mouse muscle
  • Neuromuscular junction
  • Torpedo G-AChE


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