Xenopus laevis
Stromatoxin is a peptide consisting of 34 amino acids that belongs to the structural family of ‘inhibitor cystine knot’ spider peptides. The toxin was identified using a systematical screening of the effects of toxins of several species of tarantulas on Kv2-channels of "Xenopus laevis" (the African clawed frog) . Bioassay guided fractionation and chromatography identified stromatoxin as the functional component. The full sequence of the venom was obtained in a single run of Edman sequencing and confirmed by mass spectrometry. The sequence of this toxin is ‘dctrmfgacr rdsdccphlg ckptskycaw dgti’, for an explanation of these symbols, see the list of standard amino acids.