User:Aleid Lisanne/Latisemin

Latisemin
Latisemin is a neurotoxin that can be isolated from the venom of the erabu snake. The toxin blocks L-type Ca2+ channels which causes inhibition of smooth muscle contraction.

Source
Latisemin is a venom produced in the erabu sea snake that belongs to the Elapidae family, called Laticauda semifasciata. The snakes inhabit the seas of Southern Japan, southeast Asia and Eastern Australia.

Biochemistry
Snake venoms disturb mammalian homeostasis in several ways. Latisemin, a 25-kDa and 217 amino acid protein, has neurotoxin like activities. Latisemin is part of the CRISP (cysteine-rich secretory protein) subfamily. Cysteine-rich secretory proteins (CRISPs) are a specific family of single chain polypeptides with strictly conserved cysteines in their sequences. The N-terminal amino acid sequence is: TVDFASESSNKRENQKEIVDKHNALRRSV.

Target
Latisemin blocks L-type Ca2+ channels. A L-type calcium channel is a voltage-gated channel and belongs to the Cav1 subfamily. These channels couple membrane depolarization to Ca2+-dependent intracellular signaling events.

Mode of Action
Latisemin strongly blocks depolarization (but not caffeine) induced smooth muscle contraction. The protein can inhibit the contraction of smooth muscles induced by a high concentration of potassium ions (explained by the ability to block Ca2+ channels). This is similar to some other toxins from the CRISP family, like tigrin, ablomin and triflin. The common feature of these snake venom CRISPs is that they can block smooth muscle contraction.