Alpha-conotoxins act on postsynaptic membranes, they bind to the nicotinic acetylcholine receptors (nAChR) and thus inhibit them. This toxin specifically blocks mammalian neuronal nAChR of the alpha-7/CHRNA7 (IC(50)=0.4 nM), alpha-3-beta-2/CHRNA3-CHRNB2 (IC(50)=8.4 nM) and alpha-4-beta-2/CHRNA4-CHRNB2 (IC(50)=228 nM) subtypes. VxXXB inhibits alpha-7/CHRNA7, alpha-3-beta-2/CHRNA3-CHRNB2 and alpha-4-beta-2/CHRNA4-CHRNB2 nAChR subtypes more efficiently than VxXXA and VxXXC. Homodimer. Expressed by the venom duct. The cysteine framework is XX (C-CC-C-CC-C-C-C-C). Contains 4 disulfide bonds. [desGly-95]VxXXB is a minor form. Belongs to the conotoxin D superfamily.