Altitoxin is a neurotoxin

Neurotoxin

A neurotoxin is a toxin that acts specifically on nerve cells , usually by interacting with membrane proteins such as ion channels. Some sources are more general, and define the effect of neurotoxins as occurring at nerve tissue...

 found in the South African scorpion Parabuthus transvaalicus

Parabuthus transvaalicus

Parabuthus transvaalicus is a species of scorpion from southern Africa. It is also known as "Dark Scorpion".-Description:P. transvaalicus grows to a length of , and is dark brown or black in colour. Its pincers are thin, but its tail is thickened, with the sting segment being as wide as the rest of...

. Injection of altitoxin in mice leads to akinesia, depression and death.

Source

Altitoxin is secreted by the venom gland of the South African spitting (or fattail) scorpion Parabuthus transvaalicus.

Chemistry

Altitoxin is 58 amino acid residues long and has a molecular mass of 6598 Da; it has 3 disulfide bridges. It has large homology to other toxins from the venom of Parabuthus transvaalicus

Parabuthus transvaalicus

Parabuthus transvaalicus is a species of scorpion from southern Africa. It is also known as "Dark Scorpion".-Description:P. transvaalicus grows to a length of , and is dark brown or black in colour. Its pincers are thin, but its tail is thickened, with the sting segment being as wide as the rest of...

, including bestoxin

Bestoxin

Bestoxin is a neurotoxin from the venom of the South African spitting scorpion Parabuthus transvaalicus. Most likely, it targets sodium channel function, thus promoting spontaneous and repetitive neuronal firing...

, birtoxin

Birtoxin

Birtoxin is a neurotoxin from the venom of the South African Spitting scorpion . By changing sodium channel activation, the toxin promotes spontaneous and repetitive firing.-Source:...

 ikitoxin and dortoxin.

Target

Altitoxin has sequence homology to scorpion β-toxins, suggesting it might target sodium channels. However, its depressing action following injection into mice is not in agreement with the effect of β-toxins on sodium channels. Related scorpion toxins, which include birtoxin

Birtoxin

Birtoxin is a neurotoxin from the venom of the South African Spitting scorpion . By changing sodium channel activation, the toxin promotes spontaneous and repetitive firing.-Source:...

 and bestoxin

Bestoxin

Bestoxin is a neurotoxin from the venom of the South African spitting scorpion Parabuthus transvaalicus. Most likely, it targets sodium channel function, thus promoting spontaneous and repetitive neuronal firing...

, exhibit highly divergent biological activity, indicating that the mode of action of these toxins is highly diverse.

Toxicity

An injection of 100 ng altitoxin in 20 g mouse (ED99) causes a state of akinesia and depression

Depression (mood)

Depression is a state of low mood and aversion to activity that can affect a person's thoughts, behaviour, feelings and physical well-being. Depressed people may feel sad, anxious, empty, hopeless, helpless, worthless, guilty, irritable, or restless...

. Lethality is reached at injecting 200 ng.