Three-finger toxins, a deadly weapon of elapid venom--milestones of discovery.

Three-finger toxins (TFTs) are the main venom components of snakes from Elapidae family. Amino acid sequences of more than five hundreds TFTs are determined; these toxins form one of the largest protein families present in snake venoms. The first TFT α-bungarotoxin was isolated almost half a century ago and so far it remains a valuable tool in the study of nicotinic acetylcholine receptors. TFTs possess diverse biological activities; for example, α-neurotoxins bind specifically with high affinity to nicotinic acetylcholine receptors, while cytotoxins induce non-specific lysis in great variety of cells. These toxins are widely used as instruments in different branches of life sciences. In this review the main landmarks in TFT study are considered. These are the discovery and isolation of TFTs, determination of their structure and mode of action as well as evolution and relationship within the family.