Its target is unknown, but this toxin may modulate voltage-activated calcium channels (Cav) or calcium-dependent potassium channels (KCa). Expressed by the venom duct. The cysteine framework is C-C. The differences between contryphan-R and bromocontryphan lies in the state of bromination of Trp-61. Contryphan-R. [Des-Gly1]contryphan-R. Bromocontryphan. Contryphan-R and [Des-Gly1]-contryphan-R exist in two forms, due to cis-trans isomerization at 56-Cys-hydroxyPro-57. Belongs to the O2 superfamily. Contryphan family.