Stromatoxin-1 is a 34 amino acid peptidyl toxin originally isolated from Stromatopelma calceatum tarantula¹. Structurally, Stromatoxin-1 belongs to the scaffold of structural inhibitor cysteine knot peptide family, which were shown to function as gating modifiers².

Stromatoxin-1 selectively inhibits K_V2.1, K_V2.1/9.3, and K_V4.2 channel currents (IC₅₀ of 12.7 nM, 7.2 nM and 1.2 nM respectively), and is the first high-affinity voltage gating modifier inhibitor of the K_V2.2 channel subtype (IC₅₀, 21.4 nM) to be discovered¹.