Latisemin
Encyclopedia
Latisemin is a cysteine-rich secretory protein
that can be isolated from the venom
of the Black-banded sea krait
, a sea snake indigineous to the warmer waters of the western Pacific Ocean
. It is a toxin
that inhibits cyclic nucleotide-gated ion channel
s and blocks L-type calcium channel
s, thereby reducing smooth muscle contraction.
Latisemin is a component of the venom
produced by the Erabu sea snake (Laticauda semifasciata) of the Elapidae
family and the Laticauda
genus. These sea snakes inhabit coral reef
areas in the seas of Southern Japan
, Southeast Asia
, and Australia
. Though highly venomous, this snake is comparatively unaggressive, and is in fact caught and eaten in Erabu soup in Japan.
) glycoprotein
subfamily, which are single chain polypeptides containing strictly conserved cysteines (cysteines not oxidised to cystine
and thus not providing disulfide bond
support to tertiary protein structure). They are secretory protein
s, meaning they are secreted from cells into extracellular fluid
.
s. Its mode of action is similar to that of some other snake venom
toxins from the CRISP family, like ablomin
from the Japanese Mamushi snake and triflin
from the Habu snake. They also inhibit cyclic nucleotide-gated ion channel
s.
Cysteine-rich secretory protein
Cysteine-rich secretory proteins, often abbreviated as CRISPs, are a group of glycoproteins found exclusively in vertebrates. They are a subgroup of the CRISP, antigen 5 and Pr-1 protein superfamily and are substantially implicated in the functioning of the mammalian reproductive system...
that can be isolated from the venom
Venom
Venom is the general term referring to any variety of toxins used by certain types of animals that inject it into their victims by the means of a bite or a sting...
of the Black-banded sea krait
Black-banded sea krait
The black-banded sea krait, Laticauda semifasciata, known in Okinawa as the erabu, is a member of the Laticauda genus of sea snakes. It is found in most of the warm waters of the western Pacific Ocean....
, a sea snake indigineous to the warmer waters of the western Pacific Ocean
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...
. It is a toxin
Toxin
A toxin is a poisonous substance produced within living cells or organisms; man-made substances created by artificial processes are thus excluded...
that inhibits cyclic nucleotide-gated ion channel
Cyclic nucleotide-gated ion channel
Cyclic nucleotide-gated ion channels are ion channels that function in response to the binding of cyclic nucleotides. CNG channels are nonselective cation channels that are found in the membranes of various types of cells.- Discovery :...
s and blocks L-type calcium channel
L-type calcium channel
The L-type calcium channel is a type of voltage-dependent calcium channel. "L" stands for long-lasting referring to the length of activation. Like the others of this class, the α1 subunit is the one that determines most of the channel's properties....
s, thereby reducing smooth muscle contraction.
Source
Venom
Venom is the general term referring to any variety of toxins used by certain types of animals that inject it into their victims by the means of a bite or a sting...
produced by the Erabu sea snake (Laticauda semifasciata) of the Elapidae
Elapidae
Elapidae is a family of venomous snakes found in tropical and subtropical regions around the world, terrestrially in Asia, Australia, Africa, North America and South America and aquatically in the Pacific and Indian Oceans...
family and the Laticauda
Laticauda
Laticauda is a genus of snakes from the family Hydrophiidae. Laticauda are the least adapted to sea life of all the members of Hydrophiidae; they retain the wide ventral scales typical of terrestrial snakes and have only a poorly developed tail fin...
genus. These sea snakes inhabit coral reef
Coral reef
Coral reefs are underwater structures made from calcium carbonate secreted by corals. Coral reefs are colonies of tiny living animals found in marine waters that contain few nutrients. Most coral reefs are built from stony corals, which in turn consist of polyps that cluster in groups. The polyps...
areas in the seas of Southern Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
, Southeast Asia
Southeast Asia
Southeast Asia, South-East Asia, South East Asia or Southeastern Asia is a subregion of Asia, consisting of the countries that are geographically south of China, east of India, west of New Guinea and north of Australia. The region lies on the intersection of geological plates, with heavy seismic...
, and Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
. Though highly venomous, this snake is comparatively unaggressive, and is in fact caught and eaten in Erabu soup in Japan.
Biochemistry
Latisemin has a molecular weight of 24 kDa and consists of 217 amino acids. It belongs to the CRISP (cysteine-rich secretory proteinCysteine-rich secretory protein
Cysteine-rich secretory proteins, often abbreviated as CRISPs, are a group of glycoproteins found exclusively in vertebrates. They are a subgroup of the CRISP, antigen 5 and Pr-1 protein superfamily and are substantially implicated in the functioning of the mammalian reproductive system...
) glycoprotein
Glycoprotein
Glycoproteins are proteins that contain oligosaccharide chains covalently attached to polypeptide side-chains. The carbohydrate is attached to the protein in a cotranslational or posttranslational modification. This process is known as glycosylation. In proteins that have segments extending...
subfamily, which are single chain polypeptides containing strictly conserved cysteines (cysteines not oxidised to cystine
Cystine
Cystine is a dimeric amino acid formed by the oxidation of two cysteine residues that covalently link to make a disulfide bond. This organosulfur compound has the formula 2. It is a white solid, and melts at 247-249 °C...
and thus not providing disulfide bond
Disulfide bond
In chemistry, a disulfide bond is a covalent bond, usually derived by the coupling of two thiol groups. The linkage is also called an SS-bond or disulfide bridge. The overall connectivity is therefore R-S-S-R. The terminology is widely used in biochemistry...
support to tertiary protein structure). They are secretory protein
Secretory protein
A secretory protein is any protein, whether it be endocrine or exocrine, which is secreted by a cell. Secretory proteins include many hormones, enzymes, toxins, and antimicrobial peptides.Secretory proteins are synthesized in endoplasmic reticulum....
s, meaning they are secreted from cells into extracellular fluid
Extracellular fluid
Extracellular fluid usually denotes all body fluid outside of cells. The remainder is called intracellular fluid.In some animals, including mammals, the extracellular fluid can be divided into two major subcompartments, interstitial fluid and blood plasma...
.
Target
Latisemin strongly blocks depolarization- (but not caffeine-) induced smooth muscle contraction, suggesting that it blocks L-type calcium channelL-type calcium channel
The L-type calcium channel is a type of voltage-dependent calcium channel. "L" stands for long-lasting referring to the length of activation. Like the others of this class, the α1 subunit is the one that determines most of the channel's properties....
s. Its mode of action is similar to that of some other snake venom
Snake venom
Snake venom is highly modified saliva that is produced by special glands of certain species of snakes. The glands which secrete the zootoxin are a modification of the parotid salivary gland of other vertebrates, and are usually situated on each side of the head below and behind the eye,...
toxins from the CRISP family, like ablomin
Ablomin
Ablomin is a toxin present in the venom of the Japanese Mamushi snake, which blocks L-type voltage-gated calcium channels.- Etymology :The protein ablomin is a component of the venom of the Japanese Mamushi snake, Gloydius blomhoffi...
from the Japanese Mamushi snake and triflin
Triflin
Triflin is a cysteine-rich secretory protein , which is excreted by the venom gland of the Habu snake . Triflin reduces high potassium-induced smooth muscle contraction, suggesting a blocking effect on L-type calcium channels.- Source :Triflin is a toxin derived from snake venom...
from the Habu snake. They also inhibit cyclic nucleotide-gated ion channel
Cyclic nucleotide-gated ion channel
Cyclic nucleotide-gated ion channels are ion channels that function in response to the binding of cyclic nucleotides. CNG channels are nonselective cation channels that are found in the membranes of various types of cells.- Discovery :...
s.
See also
Other snake venom proteins in the CRISP family:- AblominAblominAblomin is a toxin present in the venom of the Japanese Mamushi snake, which blocks L-type voltage-gated calcium channels.- Etymology :The protein ablomin is a component of the venom of the Japanese Mamushi snake, Gloydius blomhoffi...
from the Japanese Mamushi snake (Gloydius blomhoffi) - OphaninOphaninOphanin is a toxin found in the venom of the King Cobra , which lives throughout South East Asia. This toxin belongs to the cysteine-rich secretory protein family...
from the King Cobra (Ophiophagus hannah) - PiscivorinPiscivorinPiscivorin is a component of snake venom secreted by the Eastern Cottonmouth . It is a member of the cysteine-rich secretory protein family, which blocks voltage-dependent calcium channels.- Etymology :...
from the Eastern Cottonmouth (Agkistrodon piscivorusAgkistrodon piscivorusAgkistrodon piscivorus is a venomous snake, a species of pit viper, found in the southeastern United States. Adults are large and capable of delivering a painful and potentially fatal bite. When antagonized they will stand their ground by coiling their bodies and displaying their fangs...
) - TriflinTriflinTriflin is a cysteine-rich secretory protein , which is excreted by the venom gland of the Habu snake . Triflin reduces high potassium-induced smooth muscle contraction, suggesting a blocking effect on L-type calcium channels.- Source :Triflin is a toxin derived from snake venom...
from the Habu snake (Trimeresurus flavoviridisTrimeresurus flavoviridisTrimeresurus flavoviridis is a venomous pitviper species found in Japan in the Ryukyu Islands. No subspecies are currently recognized.-Description:...
)