8.B.17 The Sea Anemone Peptide Toxin Class III (ShI) Family

Cnidaria (sea anemone, coral, jellyfish, and hydroid) toxins target voltage-gated sodium and potassium channels. The sodium channel toxin is a member of the Toxin-4 Superfamily. It binds specifically to the sodium channel (Nav), thereby delaying its inactivation during signal transduction. Thus it strongly stimulates mammalian cardiac muscle contraction.These toxins are reviewed by Moran et al., 2009. Cnidarian toxin families, including peptide neurotoxins (voltage-gated Na+ and K+ channel-targeting toxins: NaTxs and KTxs, respectively), pore-forming toxins (actinoporins, aerolysin-related toxins, and jellyfish toxins), and the newly discovered small cysteine-rich peptides (SCRiPs).

This family belongs to the .



Fogh, R.H., W.R. Kem, and R.S. Norton. (1990). Solution structure of neurotoxin I from the sea anemone Stichodactyla helianthus. A nuclear magnetic resonance, distance geometry, and restrained molecular dynamics study. J. Biol. Chem. 265: 13016-13028.

Fraz√£o, B., V. Vasconcelos, and A. Antunes. (2012). Sea anemone (Cnidaria, Anthozoa, Actiniaria) toxins: an overview. Mar Drugs 10: 1812-1851.

Moran, Y., D. Gordon, and M. Gurevitz. (2009). Sea anemone toxins affecting voltage-gated sodium channels--molecular and evolutionary features. Toxicon 54: 1089-1101.


TC#NameOrganismal TypeExample

The Sea Anemone peptide type III neurotoxin, ShI (Fogh et al., 1990), 3-d structure known (1SHI-A).

Sea Anemone

Sh1 of Stoichactis helianthus (P19651)


Sea Anemone peptide neurotoxin Am-3; blocks Na channels.

Sea Anemone

Am-3 of Antheopsis maculata (P69928)


Anthopleurin-A, AP-A, a heart stimulant; binds voltage-gated Na+ channels (structure known) (Frazão et al. 2012).

Sea Anemone

AP-A of Anthopleura xanthogrammica (P01530)


Actitoxin-Avd1f; U-AITX-Avd1f; Av6; Neurotoxin 6 of 72 aas and 2 TMSs.

U-AITX of Anemonia viridis (sea anemone)