8.B.8 The α-KTx15 Scorpion Toxin (α-KTx15) Family

Discrepin is a scorpion peptide that blocks preferentially the I(A) currents of the voltage-dependent K(+) channel of rat cerebellum granular cells. It was isolated from the venom of the buthid scorpion Tityus discrepans and contains 38 amino acid residues with a pyroglutamic acid at the N-terminal site. Discrepin has the lowest sequence identity (approx. 50%) among the six members of the α-KTx15 sub-family of scorpion toxins (Romeo et al., 2008).

This family belongs to the Defensin Superfamily.



Huys, I., C.Q. Xu, C.Z. Wang, H. Vacher, M.F. Martin-Eauclaire, C.W. Chi, and J. Tytgat. (2004). BmTx3, a scorpion toxin with two putative functional faces separately active on A-type K+ and HERG currents. Biochem. J. 378: 745-752.

Luna-Ramírez, K., A. Bartok, R. Restano-Cassulini, V. Quintero-Hernández, F.I. Coronas, J. Christensen, C.E. Wright, G. Panyi, and L.D. Possani. (2014). Structure, molecular modeling, and function of the novel potassium channel blocker urotoxin isolated from the venom of the Australian scorpion Urodacus yaschenkoi. Mol Pharmacol 86: 28-41.

Prochnicka-Chalufour, A., G. Corzo, H. Satake, M.F. Martin-Eauclaire, A.R. Murgia, G. Prestipino, G. D'Suze, L.D. Possani, and M. Delepierre. (2006). Solution structure of discrepin, a new K+ -channel blocking peptide from the α- KTx15 subfamily. Biochemistry. 45: 1795-1804.

Romeo, S., G. Corzo, A. Vasile, H. Satake, G. Prestipino, and L.D. Possani. (2008). A positive charge at the N-terminal segment of Discrepin increases the blocking effect of K+ channels responsible for the I(A) currents in cerebellum granular cells. Biochim. Biophys. Acta. 1780: 750-755.


TC#NameOrganismal TypeExample
8.B.8.1.1Discrepin (K+ channel toxin α-KTx15.6) (solution structure solved (2AXK_A); Prochnicka-Chalufour et al., 2006)ScorpionsDiscrepin of Tityus discrepans (P84777)
8.B.8.1.2Tx3 toxin; active on A-type K+ and HERG currents (Huys et al., 2004)ScorpionsTx3 of Buthus (Mesobuthus) martensii (Q8I0L5)

Margatoxin MgTx; Toxin Ce; K+ channel toxin α-KTx of 39 aas.  Blocks Kv1.3/KCNA3 voltage-gated potassium channels of human T-lymphocytes but not Ca2+-activated K+ channel


MgTx of Centruroides elegans (bark scorpion)


K+ channel toxin 2.11 of 39 aas; also called Toxin Ce4.  


Ce4 of Centruroides elegans


Matentoxin-1 of 59 aas.


Matentoxin-1 of Mesobuthus martensii


Putative K+ channel inhibitor, αKTx30.3; SjKTx51


KTx51 of Scorpiops jendeki


Potassium channel toxin alpha-KTx 6.21; Urotoxin, of 62 aas. Blocker of voltage-gated potassium channels. It has highest activity on human voltage-gated potassium channel Kv1.2/KCNA2 channels, with an IC50 of 160 pM, whereas its affinity for other channels tested was in the nanomolar range (Luna-Ramírez et al. 2014).

α-KTx 6.21 of Urodacus yaschenkoi (Inland robust scorpion)


Potassium channel toxin alpha-KTx 6.11; male-specific potassium channel inhibitor IsTX of 63 aas and 1 N-terminal TMS.  Blocks voltage-gated potassium channels Kv1.1/KCNA1 and Kv1.3/KCNA3. Causes paralysis to crickets.

ITx 6.11 of Opisthacanthus madagascariensis (Scorpion)


TC#NameOrganismal TypeExample