blood-depressing substance-1 (bds-1), also known as kappa-actitoxin-avd4a, is a polypeptide found in the venom of the snakelocks anemone "anemonia sulcata". bds-1 is a neurotoxin that modulates voltage-dependent potassium channels, in particular kv3-family channels, as well as certain sodium channels. this polypeptide belongs to the sea anemone type 3 toxin peptide family.