Alpha-conotoxins act on postsynaptic membranes, they bind to the nicotinic acetylcholine receptors (nAChR) and thus inhibit them. Globular isomer (C1-C3; C2-C4) selectively inhibits neuronal (non-muscle) nAChR subtypes particularly human alpha-3-beta-2/CHRNA3-CHRNB2 (IC(50)=35.7 nM) and alpha-9-alpha-10/CHRNA9-CHRNA10 nAChRs (IC(50)=569 nM), while the ribbon isomer (C1-C4; C2-C3) shows weak inhibition on alpha-3-beta-2/CHRNA3-CHRNB2, but not on all other receptors tested. Expressed by the venom duct. The cysteine framework is I (CC-C-C). Alpha4/7 pattern. Both the globular (with C1-C3; C2-C4 disulfide pattern) and ribbon (C1-C4; C2-C3) isomers shows no or very weak inhibitory activity on muscle-type alpha-1-beta-1-delta-epsilon/CHRNA1-CHRNB1-CHRND-CHRNE nAChRs, alpha-4-beta-2/CHRNA4-CHRNB2, alpha-3-beta-4/CHRNA3-CHRNB4 (IC(50)=1928 nM by globular isomer), and alpha-7/CHRNA7 (IC(50)=1935 nM by globular isomer). Belongs to the conotoxin A superfamily.