Latisemin
editLatisemin 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. [1]
Source
editLatisemin 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.[1]
Biochemistry
editSnake venoms disturb mammalian homeostasis in several ways[1]. Latisemin, a 25-kDa and 217 amino acid protein [2][3], has neurotoxin like activities. Latisemin is part of the CRISP (cysteine-rich secretory protein) subfamily [4]. Cysteine-rich secretory proteins (CRISPs) are a specific family of single chain polypeptides with strictly conserved cysteines in their sequences [3]. The N-terminal amino acid sequence is: TVDFASESSNKRENQKEIVDKHNALRRSV. [5]
Target
editLatisemin blocks L-type Ca2+ channels [6]. 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
editLatisemin 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)[7]. This is similar to some other toxins from the CRISP family, like tigrin, ablomin and triflin. [1] The common feature of these snake venom CRISPs is that they can block smooth muscle contraction.
References
edit- ^ a b c d Yamazaki, Y; Koike, H; Sugiyama, Y; Motoyoshi, K; Wada, T; Hishinuma, S; Mita, M; Morita, T (2002). "Cloning and Characterization of Novel Snake Venom Proteins that Block Smooth Muscle Contraction". Eur J Biochem. 269 (11): 2708–2715. doi:10.1046/j.1432-1033.2002.02940.x. PMID 12047379.
- ^ Yamazaki, Y; Hyodo, F; Morita, T (2003). "Wide distribution of cysteine-rich secretory proteins in snake venoms: isolation and cloning of novel snake venom cysteine-rich secretory proteins". Arch. Biochem. Biophys. 412: 133–141. PMID 12646276.
- ^ a b Yamazaki, Y; Morita, T (2009). "Structure and function of snake venom cysteine-rich secretory proteins". Toxicon. 44 (3): 227–231. PMID 15302528.
- ^ Hansson, K; Kjellberg, M; Fernlund, P (2009). "Cysteine-rich secretory proteins in snake venoms form high affinity complexes with human and porcine b-microseminoproteins". Toxicon. 54: 128–137. PMID 19341830.
- ^ Osipov, A.V; Levashov, M.Y; Tsetlin, V.I; Utkin, Y.N (2005). "Cobra venom contains a pool of cysteine-rich secretory proteins". Biochem. and Biophys. Res. Commun. 328: 177–182. PMID 15670767.
- ^ Catterall, W.A; Cestèle, S; Yarov-Yarovoy, V; Yu, F.H; Konoki, K.; Scheuer, T (2007). "Voltage-gated ion channels and gating modifier toxins". Toxicon. 49: 124–141. PMID 17239913.
- ^ Yamazaki; Brown, R.L; Morita, T (2002). "Purification and cloning of toxins from elapid venoms that target cyclic nucleotide-gated ion channels". Biochemistry: 11331–11337. PMID 12234174.
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[[Category:Ion channel toxins]] [[Category:Neurotoxins]]