PROSITE documentation PDOC00435

Myotoxins family signature and profile

Myotoxins [1,2] are small basic peptides (42 to 45 residues) from the venom of rattlesnakes that cause severe muscle necrosis by a non-enzymatic mechanism. Myotoxins act extremely rapidly and serve two primary biological functions: limiting the flight of prey by causing instantaneous paralysis of the hind limbs and promoting rapid death by paralysis of the diaphragm.

Myotoxins contain six cysteines involved in three disulfide bonds as shown in the following schematic representation:

                    +------------------+
                    |                  |
          x+xC+x+xx+Cxx+xxxCxxxxxxxx+xxCxx+x+CC++xxxxxx
             |             |                 ||
             +-------------|-----------------+|
                           +------------------+

'C': conserved cysteine involved in a disulfide bond.
'+': conserved basic residue (Arg, Lys, or His).

The structure of all known myotoxins is very conserved. We chose to build a pattern based solely on the position of conserved cysteines and basic residues. We also developed a profile that covers the whole myotoxin.