long-chain neurotoxins from scorpions; Scorpion venoms contain groups of neurotoxins active specifically on mammals or insects. These peptide toxins can be classified into two main categories based on their molecular sizes and pharmacological actions. Short-chain toxins, composed of 30-40 amino acid residues with 3 or 4 disulfide bonds, affect mainly potassium or chloride channels, while long-chain toxins, composed of 60-70 amino acid residues with 4 disulfide bonds, affect mainly sodium channels and can be divided into two groups, the alpha and beta toxins. The alpha toxins bind in a voltage-dependent manner and modulate the sodium current inactivation stage, whereas binding of beta toxins is voltage-independent and interferes with the sodium current activation stage. The beta toxin class includes the groups of excitatory and depressant toxins, which differ in their mode of action and are highly specific against insects. They can selectively bind to the corresponding channels on the membrane of excitable cells, thus impairing the initial rapid depolarization phase of the action potential in nerve and muscle, resulting in neurotoxicity. This family contains the long-chain alpha and beta toxins from scorpion venom.

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               ....*....|....*....|....*....|.
gi 17737523 39 VWDNETCRRVCKEEGRSSGHCSPSLKCWCEG 69
Cdd:cd23106 15 LIENEYCNKECKKKGGSSGYCYWWLACWCEG 45

long-chain neurotoxins from scorpions; Scorpion venoms contain groups of neurotoxins active specifically on mammals or insects. These peptide toxins can be classified into two main categories based on their molecular sizes and pharmacological actions. Short-chain toxins, composed of 30-40 amino acid residues with 3 or 4 disulfide bonds, affect mainly potassium or chloride channels, while long-chain toxins, composed of 60-70 amino acid residues with 4 disulfide bonds, affect mainly sodium channels and can be divided into two groups, the alpha and beta toxins. The alpha toxins bind in a voltage-dependent manner and modulate the sodium current inactivation stage, whereas binding of beta toxins is voltage-independent and interferes with the sodium current activation stage. The beta toxin class includes the groups of excitatory and depressant toxins, which differ in their mode of action and are highly specific against insects. They can selectively bind to the corresponding channels on the membrane of excitable cells, thus impairing the initial rapid depolarization phase of the action potential in nerve and muscle, resulting in neurotoxicity. This family contains the long-chain alpha and beta toxins from scorpion venom.

                       10        20        30
               ....*....|....*....|....*....|.
gi 17737523 39 VWDNETCRRVCKEEGRSSGHCSPSLKCWCEG 69
Cdd:cd23106 15 LIENEYCNKECKKKGGSSGYCYWWLACWCEG 45

The "knottin" fold is stable cysteine-rich scaffold, in which one disulfide bridge crosses the macrocycle made by two other disulfide bridges and the connecting backbone segments. Members include plant lectins/antimicrobial peptides, plant proteinase/amylase inhibitors, plant gamma-thionins, and arthropod defensins.

                       10        20        30
               ....*....|....*....|....*....|....*
gi 17737523 35 GPCAVWDNetCRRVCKEEGRSSGHCSP-SLKCWCE 68
Cdd:cd00107  1 GTCFSDSY--CDKECKKKGASGGYCYGqGLACWCY 33