Stromatoxin is a spider toxin that blocks certain delayed-rectifier and A-type voltage-gated potassium channels.
Stromatoxin was first identified in the venom of the African tarantula Stromatopelma calceatum (the featherleg baboon spider), from which it derives its name.
The sequence of this toxin is ‘dctrmfgacr rdsdccphlg ckptskycaw dgti’, for an explanation of these symbols, see the list of standard amino acids.
The toxin therefore acts as a gating modifier, shifting the activation of the channel to more depolarized potentials.
Its target channels can be found in cardiac tissue, neurons and smooth muscle cells.
Escoubas, Pierre; Diochot, Sylvie; Ce'Le'Rier, Marie-Louise; Nakajima, Terumi; Lazdunski, Michel (2002), "Novel Tarantula Toxins for Subtypes of Voltage-Dependent Potassium Channels in the Kv2 and Kv4 Subfamilies", Molecular Pharmacology, 62 (1): 48–57, doi:10.1124/mol.62.1.48, PMID 12065754.
(2007), "Kv2 subunits underlie slowly inactivating potassium current in rat neocortical pyramidal neurons", J.
(2003), "Structural basis of binding and inhibition of novel tarantula toxins in mammalian voltatge-dependent potassium channels", Chem.
(2006), "Characteristics of IA currents in adult rabbit cerebellar Purkinje cells", Brain Res., 1096 (1): 85–96, doi:10.1016/j.brainres.2006.04.048, PMID 16716270, S2CID 35757890.