Hongotoxin Explained
Hongotoxin (HgTX) is an ion channel toxin, which blocks Shaker-type (Kv1) K+ channels. The toxin is derived from the venom of Centruroides limbatus,[1] a Central American scorpion found meanly in Costa Rica, Honduras and Panama.[2]
Chemistry
Hongotoxin belongs to the short scorpion toxin superfamily. Potassium channel inhibitor family. Alpha-KTx 2 subfamily.[1]
There are five subtypes known of the hongotoxin peptide. HgTX1 is 39 amino acids long and shows an overall amino acid sequence homology of 89% to margatoxin (MgTX).[1]
Target
Hongotoxin (HgTX) targets are Shaker-type (Kv1) K+ channels.
HgTX1 shows high affinity with Kv1.1, Kv1.2, Kv1.3 voltage-gated potassium channels, but much lower affinity with Kv1.6 (see table 1 and 2[1]).
HgTX2,[3] HgTX3,[4] HgTX4[5] and HgTX5[6] are potent selective inhibitors of Kv1 voltage-gated potassium channels (By similarity).
| table 1 | | IC50 | | |
|---|
| Kv1.1 | Kv1.2 | Kv1.3 | Kv1.6 |
|---|
| HgTX1 | 31 | 170 | 86 | 6,000 |
| MgTx | 144 | 675 | 230 | ND | |
ND, not determined. All measurements in
pM| table 2 | | Ki | | |
|---|
| Kv1.1 | Kv1.2 | Kv1.3 | Kv1.6 |
|---|
| HgTX1 | 0.08 | 0.09 | 0.24 | 8.7 |
| MgTx | 0.52 | 0.21 | 0.31 | 9.4 | |
All measurements in
pMMode of action
The mode of action is not yet known.
External links
- Pragl B, Koschak A, Trieb M, etal . Synthesis, characterization, and application of cy-dye- and alexa-dye-labeled hongotoxin(1) analogues. The first high affinity fluorescence probes for voltage-gated K+ channels . Bioconjugate Chemistry . 13 . 3 . 416–25 . 2002 . 12009929 . 10.1021/bc015543s.
Notes and References
- Koschak A, Bugianesi RM, Mitterdorfer J, Kaczorowski GJ, Garcia ML, Knaus HG . Subunit composition of brain voltage-gated potassium channels determined by hongotoxin-1, a novel peptide derived from Centruroides limbatus venom . The Journal of Biological Chemistry . 273 . 5 . 2639–44 . January 1998 . 9446567 . 10.1074/jbc.273.5.2639. free .
- Web site: Jan Ove . Rein . Centruroides limbatus . The Scorpion Files .
- https://www.ncbi.nlm.nih.gov/entrez/viewer.fcgi?db=protein&id=34925057 Hongotoxin-2
- https://www.ncbi.nlm.nih.gov/entrez/viewer.fcgi?db=protein&id=34925059 Hongotoxin-3
- https://www.ncbi.nlm.nih.gov/entrez/viewer.fcgi?db=protein&id=34925062 Hongotoxin-4
- https://www.ncbi.nlm.nih.gov/entrez/viewer.fcgi?db=protein&id=34925065 Hongotoxin-5
