Ablomin is a

toxin A toxin is a naturally occurring poison produced by metabolic activities of living cells or organisms. They occur especially as proteins, often conjugated. The term was first used by organic chemist Ludwig Brieger (1849–1919), derived ...

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 ''Gloydius blomhoffii'', commonly known as the mamushi,Mehrtens JM (1987). ''Living Snakes of the World in Color''. New York: Sterling Publishers. 480 pp. . Japanese moccasin, Japanese pit viper, Qichun snake, Salmusa or Japanese mamushi,Gumprec ...

snake, ''

Gloydius blomhoffii ''Gloydius blomhoffii'', commonly known as the mamushi,Mehrtens JM (1987). ''Living Snakes of the World in Color''. New York: Sterling Publishers. 480 pp. . Japanese moccasin, Japanese pit viper, Qichun snake, Salmusa or Japanese mamushi,Gumprec ...

''. The term ‘ablomin’ is an acronym derived from ''

Agkistrodon ''Agkistrodon'' is a genus of pit vipers commonly known as American moccasins.Crother, B. I. (ed.). 2017. ''Scientific and Standard English Names of Amphibians and Reptiles of North America North of Mexico, with Comments Regarding Confidence in ...

blomhoffi'', an old name for this snake.

Sources

The protein can be found in the venom of the Japanese Mamushi snake, a member of the

Viperidae Vipers are snakes in the family Viperidae, found in most parts of the world, except for Antarctica, Australia, Hawaii, Madagascar, New Zealand, Ireland, and various other isolated islands. They are venomous snake, venomous and have long (relat ...

family.

Chemistry

Ablomin is part of the Cystein-Rich Secretory Protein (CRISP) family. CRISPs comprise a particular group of snake venom proteins distributed among the venom of several families of snakes, such as

elapids Elapidae (, commonly known as elapids , from , variant of "sea-fish") is a family of snakes characterized by their permanently erect fangs at the front of the mouth. Most elapids are venomous, with the exception of the genus '' Emydocephalus' ...

, colubrids and

vipers Vipers are snakes in the family Viperidae, found in most parts of the world, except for Antarctica, Australia, Hawaii, Madagascar, New Zealand, Ireland, and various other isolated islands. They are venomous and have long (relative to non-viper ...

. The protein exists of 240

amino acids Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although over 500 amino acids exist in nature, by far the most important are the Proteinogenic amino acid, 22 α-amino acids incorporated into p ...

, coded by an

mRNA In molecular biology, messenger ribonucleic acid (mRNA) is a single-stranded molecule of RNA that corresponds to the genetic sequence of a gene, and is read by a ribosome in the process of Protein biosynthesis, synthesizing a protein. mRNA is ...

of 1336

base pairs A base pair (bp) is a fundamental unit of double-stranded nucleic acids consisting of two nucleobases bound to each other by hydrogen bonds. They form the building blocks of the DNA double helix and contribute to the folded structure of both DNA ...

. Structurally, it is composed of three distinct regions: an N-terminal protein domain, a hinge region and a C-terminal cystein-rich domain. It has a

molecular mass The molecular mass () is the mass of a given molecule, often expressed in units of daltons (Da). Different molecules of the same compound may have different molecular masses because they contain different isotopes of an element. The derived quan ...

of 25

kDa The dalton or unified atomic mass unit (symbols: Da or u, respectively) is a unit of mass defined as of the mass of an unbound neutral atom of carbon-12 in its nuclear and electronic ground state and at rest. It is a non-SI unit accepted f ...

. Ablomin shows great sequence homology with triflin (83.7%) and latisemin (61.5%), two other snake venom components of the CRISP family, which also target voltage-dependent calcium channels. In addition, it shows partial homology with helothermine (52.8%), a venom protein of the Mexican beaded lizard; this protein, however, targets other ion channels than ablomin.

Target

Ablomin reduces potassium-induced contraction of smooth muscles, suggesting that it blocks L-type voltage-gated calcium channels. Moreover, ablomin may slightly inhibit rod-type

cyclic nucleotide-gated ion channel Cycle, cycles, or cyclic may refer to: Anthropology and social sciences * Cyclic history, a theory of history * Cyclical theory, a theory of American political history associated with Arthur Schlesinger, Sr. * Social cycle, various cycles in ...

s ( CNGA1) channels.

Toxicity

Ablomin affects high potassium-induced contraction of arterial smooth muscle in rat-tails in a concentration-dependent matter. Reduction of arterial smooth muscle contraction in a rat-tail results in vasodilation of the rat-tails artery, which may lead to hypothermia. Blocking other L-type voltage gated Ca2+ channels, for instance in the heart, may lead to arrhythmias and even cardiac arrest.

References

{{reflist, refs= *{{cite journal , last1=Yamazaki , first1=Y , last2=Koike , first2=H , last3=Sugiyama , year=2002 , first3=Y , last4=Motoyoshi , first4=K , last5=Wada , first5=T , last6=Hishinuma , first6=S , last7=Mita , first7=M , last8=Morita , first8=T , s2cid=30934694 , title=Cloning and Characterization of Novel Snake Venom Proteins that Block Smooth Muscle Contraction , journal=Eur J Biochem , volume=269 , pmid=12047379 , issue= 11, pages=2708–2715 , doi=10.1046/j.1432-1033.2002.02940.x , doi-access=free *{{cite journal , last1=Matsunaga , first1=Y , last2=Yamazaki , first2=Y , year=2009 , last3=Hyodo , first3=F , last4=Sugiyama , first4=Y , last5=Nozaki , first5=M , last6=Morita , first6=T , title=Structural Divergence of Cysteine-Rich Secretory Proteins in Snake Venoms , journal=J Biochem , volume=145 , pmid=19106157 , issue=3 , pages=365–375 , doi=10.1093/jb/mvn174 *{{cite journal , last1=Yamazaki , first1=Y , last2= Morita, first2= T, year=2004 , title=Structure and Function of Snake Venom Cysteine-Rich Secretory Proteins , journal=Toxicon , volume=44 , pmid=15302528 , issue= 3, pages=227–231 , doi=10.1016/j.toxicon.2004.05.023 , bibcode=2004Txcn...44..227Y Ion channel toxins Neurotoxins Snake toxins

Etymology

Sources

Chemistry

Target

Toxicity

See also

References