Modulator - Issue No. 26

In Focus: Labeled α-Bungarotoxin

α-Bungarotoxin is a 74 amino acid peptidyl toxin isolated from the venom of the banded krait snake, Bungarus multicinctus1.

α-Bungarotoxin blocks postsynaptic neuromuscular transmission via competitive inhibition of nicotinic ACh receptors (nAChRs) with an IC50 of 3.5 x 10-10 M, thereby prevents the depolarizing action on postsynaptic membranes and blocks neuromuscular transmission2.

The toxin is selective for nAChR α7 receptors (IC50 value of 1.6 nM) and nAChR α3/β4 receptors (IC50 value of > 3 μM)3,4. α-Bungarotoxin also binds to and blocks a subset of GABAA receptors (GABAARs) that contain the GABAAR β3 subunit. In particular, α-Bungarotoxin blocks GABAARs that contain interfaces between adjacent β3 subunits5.

Labeled α-Bungarotoxin is ideally used to label nAChR α7 receptors, and in many cases to localize neuromuscular junctions6,7.

Alomone Labs is pleased to offer α-Bungarotoxin-ATTO-488 (#B-100-AG), labeled with a green fluorescent dye and α-Bungarotoxin-Biotin (#B-100-B), labeled with biotin.


b-100-ag_pic
Alomone Labs α-Bungarotoxin-ATTO-488 in whole mount staining of mice Gastrocnemius muscleWhole mount staining of mice Gastrocnemius muscle was stained with the neuromuscular junction marker α-Bungarotoxin-ATTO-488 (#B-100-AG), (green) at 1:50 (A) and 1:100 (B) ratios.The images were taken using Nikon Epifluorescence microscopy at X100 magnification and are a kind gift from Dr. Eran Perlsson, Dept. of Physiology and Pharmacology, Tel-Aviv University.


b-100-b_pic
Bungarotoxin-Biotin binding sites co-localize GABAergic neurons expressing parvalbumin in mouse hippocampal CA1 regionA. Free floating mouse brain sections were incubated with α-Bungarotoxin-Biotin (#B-100-B), (1:10,000) followed by streptavidin-Alexa 488 (green). B. Same sections were stained with antiparvalbumin, followed by goat anti-mouse labeled with Texas red isothiocyanate (TRITC). C. Merge of A and B demonstrates sites of colocalization (vertical arrows) confirming reports that a subset of hippocampal interneurons express nAChR α7. DAPI is used as the counterstain.


References
1. Ohta, M. et al. (1987) FEBS Lett. 222, 79.
2. Wilson, P.T. et al. (1988) Mol. Pharmacol. 34, 643.
3. Wilson, S.P. and Kirshner, N. (1977) J. Neurochem. 28, 687.
4. Garcia-Guzman, M. et al. (1995) Eur. J. Neurosci. 7, 647.
5. McCann, C.M. et al. (2006) Proc. Natl. Acad. Sci. U.S.A. 103, 5149.
6. Fertuck, H.C. and Salpeter, M.M. (1974) Proc. Natl. Acad. Sci. U.S.A. 71, 1376.
7. Ravdin, P. and Axelrod, D. (1977) Anal. Biochem. 80, 585.