Alpha-conotoxins act on postsynaptic membranes, they bind to the nicotinic acetylcholine receptors (nAChR) and thus inhibit them. Both the globular (with C1-C3; C2-C4 disulfide pattern) and ribbon (C1-C4; C2-C3) isomers reversibly inhibit human muscle-type alpha-1-beta-1-delta-epsilon/CHRNA1-CHRNB1-CHRND-CHRNE nAChRs (IC(50)=116 nM and IC(50)=643 nM, respectively) (PubMed:34062129). Both isomers also inhibit alpha-7/CHRNA7 and alpha-9-alpha-10/CHRNA9-CHRNA10 (IC(50)=1113 nM by globular isomer) nAChRs (PubMed:34062129). Expressed by the venom duct. The cysteine framework is I (CC-C-C). Alpha3/5 pattern. Both the globular (with C1-C3; C2-C4 disulfide pattern) and ribbon (C1-C4; C2-C3) isomers shows no or very weak activity on alpha-3-beta-2/CHRNA3-CHRNB2, alpha-3-beta-4/CHRNA3-CHRNB4, and alpha-4-beta-2/CHRNA4-CHRNB2. Belongs to the conotoxin A superfamily.