Aligned sequences of µ-conotoxin GIIIA, KIIIA, ddKIIIA, and ddKIIIA[K7X]. GIIIA and KIIIA have the three canonical disulfide-bridges of µ-conotoxins: between 1st and 4th, 2nd and 5th, and 3rd and 6th cysteine residues (as indicated by lines above the sequences). ddKIIIA and ddKIIIA[K7X] have the same bridge framework except the first disulfide bridge was deleted and the second was replaced with a diselenide bridge. The long moniker of ddKIIIA[K7X] is KIIIA[C1A,C2U,K7X,C9A,C5U], where in the present report, residue X at position 7 was either Ala, Asp, Gly, Leu, Lys (i.e., ddKIIIA), Phe, Ser, Thr, Val, or diaminoproprionate (dap). O, hydroxyproline; #, amide; U, selenocysteine; shading, disulfide- or diselenide-bridged residues.