Scorpion potassium channel toxin

Scorpion potassium channel toxins (KTxs) are 20–95 amino acid peptides stabilized by two, three or four disulfide bonds, which make their tertiary structure highly stable. KTxs have the highly conserved secondary structural arrangement α/β stabilized by cysteines (CSα/β) and, most of them, have conserved residues which are responsible for block of the ion conduction pore and promote a high affinity binding within the potassium channel pore vestibule, such as a lysine residue and an aromatic residue at 6.6 Angstroms from the ?carbon of that lysine, respectively (Dauplais et al.,1997 ).

Scorpion KTxs were originally classified into three families named α, β and γ (Tytgat et al., 1999 ), all of them have the above mentioned, highly conserved, α/β structural arrangement. Latter, scorpion KTxs presenting a different structural arrangement, with only two α–helices stabilized by two disulfide bonds, CSα/α, were described, and they were named κ–KTxs (Chagot et al., 2005, Srinivasan et al., 2002, Camargos et al., 2011 ). Among the almost 200 scorpion KTxs described until now, the α–KTx family contains about 120 peptides thus far, which are classified in 30 subfamilies, based on their amino acid homology (Rodriguez de la Vega et al., 2004, Tytgat et al., 1999, Zhu et al.,2010 ).

The table below lists all potassium channel–specific scorpion toxins classified until now. We would like to thank Dr. Ricardo C. Rodriguez de la Vega and Prof. Lourival D. Possani for their help in establishing this list.