The three-finger protein family is a family of proteins that share similar 3-dimensional structure. They are found in a wide variety of organisms including snakes. In snakes and kraits, venomous toxins largely consist of those with a three-finger structure. The structure of the α-BTX has been most studied; its three-finger structure consists of a hydrophobicglobular core from which 3 beta-pleated-sheet loops extend as well as a C-terminus. Within the family of three-finger α-neurotoxins, the protein structure is further subcategorized as short chain, long chain, atypical long chain and non conventional α-neurotoxins. This subclassification describes additional structural aspects of the toxin as well as the receptors they act on. For example, α-BTX is a long chain toxin meaning it is composed of 66-70 amino acids and possesses a three-finger structure. Long chain toxins act on nAchR in both muscle and neurons whereas short chain α-neurotoxins act on nAchR in muscle only. While all α-neurotoxins of the three-finger family will act on muscle nAchR, these differences in structure determine selectivity of the toxin for its receptor as well as affinity and dissociation.
Bungarotoxin
Kurtoxin
Alpha-neurotoxin
Neurotoxin
Dinotoxin
Kaliotoxin
Latrotoxin
Agitoxin