Kappa-Theraphotoxin-Hm1a (KAPPA-TRTX-HM1A) Heteroscodra Maculata Recombinant Protein

Function: Inhibitor of voltage-gated potassium channels. It inhibits Kv2.1/KCNB1, Kv2.2/KCNB2, Kv4.1/KCND1, Kv4.2/KCND2 and Kv4.3/KCND3 potassium channels. May act by shifting activation of the channel to more depolarized voltages. The toxin binding sites may be situated on the S3-S4 extracellular linker of the channel. One, two, three or four toxin molecules may bind the Kv2.1/KCNB1 channel. May need to partition into the membrane in order to bind to the channel. Intracerebroventricular injection into mice induces convulsions, spasms, tremors, and death. Ref.1

Subcellular location: Secreted.

Tissue specificity: Expressed by the venom gland.

Domain: The presence of a 'disulfide through disulfide knot' structurally defines this protein as a knottin

By similarity.

Miscellaneous: IC50 is 280 nM on Kv4.1/KCND1, whereas percentage of current inhibition are 23% on Kv2.1/KCNB1 at 100 nM, 19.7% on Kv2.2/KCNB2 at 100 nM, 39% on Kv4.2/KCND2 at 300 nM, and 43% on Kv4.3/KCND3 at 300 nM (Ref.1).

Sequence similarities: Belongs to the huwentoxin-1 family.

Mass spectrometry: Molecular mass is 3994.59 Da from positions 1 - 35. Determined by MALDI. Ref.1