Alpha-conotoxins act on postsynaptic membranes, they bind to the nicotinic acetylcholine receptors (nAChR) and thus inhibit them (PubMed:10320362, PubMed:28238803). CnIA and CnIB block muscular nAChR alpha-1/gamma and alpha-1/delta subunits (PubMed:10320362). Expressed by the venom duct. The cysteine framework is I (CC-C-C). Alpha3/5 pattern. CnIA. CnIB. CnIK. [Hyp]CnIK. Found in injectable (milked) (IV) venom. Belongs to the conotoxin A superfamily.