Sandbox Reserved 932: Difference between revisions
From Proteopedia
Jump to navigationJump to search
No edit summary |
mNo edit summary |
||
| Line 22: | Line 22: | ||
=== Denmotoxin belongs to a family of non-conventional three-finger toxins === | === Denmotoxin belongs to a family of non-conventional three-finger toxins === | ||
Three-finger toxins (3FTXs) are the most common family of snake venom proteins; these venoms can be found in elapid, colubrid and hydrophiid snakes and include toxins such as α-cobratoxin and α-bungarotoxin. 3FTXs are non-enzymatic proteins which form a structurally conserved superfamily whose members all share a highly conserved structure. The core structure of 3FTXs is formed by <scene name='57/579702/Three_fingers/1'>three β-stranded polypeptide loops</scene> joined together by four conserved disulphide bridges located in the <scene name='57/579702/3ftx_beta_strands/2'>core</scene> of the protein. Despite the similarities in the structure of different toxins belonging to the family, the 3FTXs from various venoms have a variety of receptors/acceptors and exhibit differential responses in their targets. The members of the family can vary slightly in the length and type of twists of the tree loops. | |||
Denmotoxin shares approximately 30% sequence similarity with other 3FTXs with an exception of exhibiting approximately 50% sequence similarity with another colubrid snake venom α-colubritoxin. Despite the relatively low sequence similarity, denmotoxin possesses all the residues needed to maintain the 3 finger fold. A large part of the sequence similarity between denmotoxin and other 3FTXs is due to the highly conserved disulphides and a number of structurally important residues. | |||
Three-finger toxins (3FTXs) are the most common family of snake venom proteins with a conserved structure. The core structure of 3FTXs is formed by <scene name='57/579702/Three_fingers/1'>three polypeptide loops</scene> joined together by disulphide bridges. Denmotoxin has several features which classify it as a non-conventional 3FTX. It differs structurally from other 3FTX venoms by its seven additional N-terminal amino acid residues; this unusually long N-terminus is unstructured and is hypothesized to gyrate above the core of the protein. There is also an additional fifth disulphide bridge at the first loop of the protein, which is not present in most 3FTXs. Another unique feature of denmotoxin is the twist at the tip of the central loop originating from a kink in a proline residue (Pro40). At the central loop, the charge is also negative, an arginine residue has been replaced with an aspartic acid, which is unusual for the proteins of the family. | Three-finger toxins (3FTXs) are the most common family of snake venom proteins with a conserved structure. The core structure of 3FTXs is formed by <scene name='57/579702/Three_fingers/1'>three polypeptide loops</scene> joined together by disulphide bridges. Denmotoxin has several features which classify it as a non-conventional 3FTX. It differs structurally from other 3FTX venoms by its seven additional N-terminal amino acid residues; this unusually long N-terminus is unstructured and is hypothesized to gyrate above the core of the protein. There is also an additional fifth disulphide bridge at the first loop of the protein, which is not present in most 3FTXs. Another unique feature of denmotoxin is the twist at the tip of the central loop originating from a kink in a proline residue (Pro40). At the central loop, the charge is also negative, an arginine residue has been replaced with an aspartic acid, which is unusual for the proteins of the family. | ||
