Pandinotoxin
From Wikipedia, the free encyclopedia
| Pandinotoxin | |
|---|---|
 Schematic diagram of the three-dimensional of Pandinotoxin | |
| Identifiers | |
| Organism | |
| Symbol | N/A |
Pandinotoxins are toxins from the venom of the emperor scorpion Pandinus imperator. They are selective blockers of voltage-gated potassium channels [1]
The source for the pandinotoxins is the venom of the scorpion Pandinus imperator.[1]
Chemistry
Family
The toxins of the family are designated pandinotoxin (PiTX)-Kα, PiTX-Kβ, and PiTX-Kγ [2] They are members of the α-KTx family of scorpion toxins.[1]
Structure and homology
| The sequences of Pandinotoxins |
|---|
|
CTX
PiTXK- α
PiTXK- β
PiTX-K γ
Figure 1: Sequence of Pandinotoxins. Adapted from Solution Structure for Pandinus Toxin K-R (PiTX-KR) [1] |
Pandinotoxin Kα and -β
The amino acid sequences of PiTX-K α and PiTX-K β are identical, except for the seventh amino acid: a proline in PiTX-Kα and a glutamic acid in PiTX-Kβ [2](see Fig.1).
PiTX-Kα and PiTX-Kβ are 35-residue peptides, which are found to have an α-helix from residues 10 to 21 and two β-sheets (β 1 is from residues 26-28, β 2 is from residues 33-35). One face of the α-helix is anchored to the β-sheet by three disulfide bonds which are conserved in all members of the charybdotoxin family (R-K toxins).[1] PiTX-K α and PiTX-K β have only two β-sheets whereas other members of the family have three additional amino acid residues at the N-terminal portion, which forms a third β-sheet.[1]
Pandinotoxin Kγ
Pandinotoxin Kγ has not yet been investigated.
Target
Pandinotoxins are the most potent inhibitors of the rapidly inactivating A-type voltage-gated potassium channels.[3] They also block the delayed rectifier, slowly inactivating channels of the subfamily A member 2 (Kv1.2/KCNA2) [1] and they can reversibly block the shaker B potassium-channels (Kv1.1 sub-family).[4]
