This peptide is similar to the potassium channel toxin ShK, but does not show activity on potassium channels. It appears that Lys-19, which is expected to occupy the pore of the channel, is not sufficiently accessible for binding, and therefore that this peptide must have a distinct functional role that does not involve potassium channels. It is noteworthy that this peptide is much more stable in the presence of trypsin, chymotrypsin and pepsin than the toxin ShK. Does not show activity against grass shrimp (Palaemonetes sp.) and brine shrimp (A.nauplii). Does not show activity on the voltage-gated potassium channels tested (rKv1.1/KCNA1, rKv1.2/KCNA2, hKv1.3/KCNA3, rKv1.4/KCNA4, rKv1.5/KCNA5, rKv1.6/KCNA6, Shaker IR/Sh, rKv4.2/KCND2, Kv11.1/KCNH2/ERG1, hKv10.1/KCNH1/EAG1). Belongs to the sea anemone type 1 potassium channel toxin family. Type 1a subfamily.