Monomer: binds with high affinity to muscular (alpha-1-beta-1-gamma-delta/CHRNA1-CHRNB1-CHRNG-CHRND) nAChR (tested on Torpedo californica, Kd=0.2-4.5 nM) and neuronal alpha-7/CHRNA7 nicotinic acetylcholine receptors (Kd=13-105 nM) (PubMed:18381281, PubMed:9305882, PubMed:22223648). Also inhibits GABA(A) channels (PubMed:26221036). Heteropentamer targets studied are composed of alpha-1-beta-3-gamma-2 (GABRA1-GABRB3-GABRG2) subunits (IC(50)=236 nM), alpha-1-beta-2-gamma-2 (GABRA1-GABRB2-GABRG2) subunits (IC(50)=469 nM), alpha-2-beta-2-gamma-2 (GABRA2-GABRB2-GABRG2) subunits (IC(50)=485 nM), alpha-5-beta-3-gamma-2 (GABRA5-GABRB3-GABRG2) subunits (IC(50)=635 nM), and alpha-2-beta-3-gamma-2 (GABRA2-GABRB3-GABRG2) subunits (IC(50)=1099 nM) (activated by 10 uM GABA) (PubMed:26221036). Homodimer: binds with high affinity (but lower than the monomeric form) to muscular (IC(50)=9.7 nM) and with low affinity to neuronal alpha-7/CHRNA7 nAChRs (IC(50)=1370 nM) (PubMed:22223648). However, it acquires (compared to the monomeric form) the capacity to block alpha-3/beta-2 (CHRNA3/CHRNB2) nAChRs (PubMed:18381281). Heterodimer with cytotoxin 3 (AC P01446): is slightly more active than the homodimer in inhibiting alpha-7/CHRNA7 nAChR and is considerably more active in blocking the alpha-3-beta-2/CHRNA3-CHRNB2 nAChR. Monomer, homo- or heterodimer with cytotoxins 1 (P60305), 2 (AC P01445), and 3 (AC P01446); disulfide-linked. Expressed by the venom gland. In homodimer alpha-cobratoxin, selective reduction of Cys(26)-Cys(30) in one subunit does not affect the activity against the alpha-7/CHRNA7 nAChR, whereas its reduction in both subunits almost prevents alpha-7/CHRNA7 nAChR recognition. On the contrary, reduction of one or both Cys(26)-Cys(30) disulfide bonds in the homodimer considerably potentiates inhibition of the alpha-3-beta-2/CHRNA3-CHRNB2 nAChR by the toxin. The monomeric form has no effect on alpha-3/beta-2 (CHRNA3/CHRNB2) nAChR (PubMed:18381281). It does not show any blockade of the nicotine-evoked release of dopamine (PubMed:9840221) and does not affect ACh release. Exists in two forms, due to cis-trans isomerization at 6-Thr-Pro-7 (Probable). In the dimeric form, the Pro-7 is extended away from the toxin core whereas in the monomeric form, Pro-7 makes a turn (PubMed:22223648). Belongs to the snake three-finger toxin family. Long-chain subfamily. Type II alpha-neurotoxin sub-subfamily.