Arg-Ser-Cys3-Ile-Asp-Thr-Ile-Pro-Lys-Ser-Arg-Cys12-Thr-Ala-Phe-Gln-Cys17-Lys-His-Ser-Met-Lys-Tyr-Arg-Leu-Ser-Phe-Cys28-Arg-Lys-Thr-Cys32-Gly-Thr-Cys35-OHDisulfid e bonds between Cys3-Cys35, Cys12-Cys28 and Cys17-Cys32
ShK has been isolated from the venom of the Carribean seaanemone Stoichactis helianthus. This toxin inhibits voltagedependentpotassium channels. It blocks Kv1.3 (KCNA3)potently and also Kv1.1 (KCNA1), Kv1.4 (KCNA4), and Kv1.6(KCNA6) respectively with 11 pM,16 pM and 165 pM.