This toxin binds and inhibits rat muscle adult alpha-1-beta-1-delta-epsilon/CHRNA1-CHRNB1-CHRND-CHRNE (IC(50)=3.1 uM) and fetal alpha-1-beta-1-gamma-delta/CHRNA1-CHRNB1-CHRNG-CHRND (IC(50)=5.6 uM) nicotinic acetylcholine receptors (nAChR) (PubMed:26448325). It shows a very low inhibition on rat neuronal alpha-3-beta-2/CHRNA3-CHRNB2 nAChR (IC(50)=50.2 uM) nAChR (PubMed:26448325). It does not inhibit human glycine receptor (homopentamer composed of alpha-1 subunits), but seems to potentiate it (about 2-fold increased activity). It binds to the acetylcholine-binding pocket and acts as a competitive antagonist (PubMed:26448325). Expressed by the venom gland. LD(50) is 2 mg/kg by intravenous injection into mouse. Does not inhibit human alpha-7/CHRNA7, alpha-9-alpha-10/CHRNA9-CHRNA10, alpha-3-beta-2/CHRNA3-CHRNB2, alpha-4-beta-4/CHRNA4-CHRNB4, alpha-4-beta-2/CHRNA4-CHRNB2 and rat alpha-3-beta-4/CHRNA3-CHRNB4 nAChR. Does not inhibit human GABA(A) receptor (heteropentamer composed of alpha-1-beta-2-gamma-2 subunits and homopentamer composed of rho-1 subunits). Hassan-Puttaswamy et al., 2015 propose to call this novel class of nAChR competitive inhibitors 'OMEGA toxins'. Is classified as a P-type cytotoxin, since a proline residue stands at position 28 (Pro-31 in standard classification). Belongs to the snake three-finger toxin family. Short-chain subfamily.