Ablomin is a
toxin present in 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,Gumprech ...
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,Gumprech ...
snake, ''
Gloydius blomhoffii''. The term ‘ablomin’ is an acronym derived from ''
Agkistrodon blomhoffi'', an old name for this snake.
Sources
The protein can be found in 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,Gumprech ...
snake, a member of the
Viperidae 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,
colubrids and
vipers.
The protein exists of 240
amino acids
Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although hundreds of amino acids exist in nature, by far the most important are the alpha-amino acids, which comprise proteins. Only 22 alpha am ...
, coded by an
mRNA 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 of 25
kDa.
Ablomin shows great sequence
homology
Homology may refer to:
Sciences
Biology
*Homology (biology), any characteristic of biological organisms that is derived from a common ancestor
* Sequence homology, biological homology between DNA, RNA, or protein sequences
*Homologous chrom ...
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 channels (
CNGA1
Cyclic nucleotide-gated channel alpha 1, also known as CNGA1, is a human gene encoding an ion channel protein. Heterologously expressed CNGA1 can form a functional channel that is permeable to calcium. In rod photoreceptors, however, CNGA1 forms ...
) 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.
See also
*Other snake venom proteins in the CRISP family:
**
Piscivorin Piscivorin is a component of snake venom secreted by the Eastern Cottonmouth (''Agkistrodon piscivorus piscivorus''). It is a member of the cysteine-rich secretory protein (CRISP) family, which blocks voltage-dependent calcium channels.
Etymology ...
from the Eastern Cottonmouth
**
Triflin from the Habu snake
**
Ophanin from the King Cobra
**
Latisemin from the Erabu snake
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 ]
*
[{{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 ]
Ion channel toxins
Neurotoxins
Vertebrate toxins