Isoglobotriosylceramide,
Gal(α1→3)Gal(β1→4)
Glcβ(1→1)
Cer
Cer, or CER may refer to:
Environment
* Certified Emission Reduction, emission units
Statistics
* Control event rate, a statistical value in epidemiology
* Crossover error rate, a statistical value in a biometric system
Information Technology
...
, abbreviated as
iGb3, is an iso-globo-series of
glycosphingolipid
Glycosphingolipids are a subtype of glycolipids containing the amino alcohol sphingosine. They may be considered as sphingolipids with an attached carbohydrate. Glycosphingolipids are a group of lipids (more specifically, sphingolipids) and are a ...
, which mysteriously disappeared in most mammals studied (pig, mouse, and human), except trace amount reported in the
thymus
The thymus is a specialized primary lymphoid organ of the immune system. Within the thymus, thymus cell lymphocytes or ''T cells'' mature. T cells are critical to the adaptive immune system, where the body adapts to specific foreign invaders. ...
.
iGb3 was discovered in
canine
Canine may refer to:
Zoology and anatomy
* a dog-like Canid animal in the subfamily Caninae
** '' Canis'', a genus including dogs, wolves, coyotes, and jackals
** Dog, the domestic dog
* Canine tooth, in mammalian oral anatomy
People with the ...
and rat intestines among iso-globo-series of glycosphingolipids. First NMR spectrums for standard iGb3 were published by Dr. Tomoya Ogawa.
The physiological function of
iGb3 is not clear. It has been identified as a
CD1d- presented self-antigen for an innate type of immune cells termed as
Natural Killer T (NKT) cells. Extensive biochemical studies by multiple methods including
HPLC
High-performance liquid chromatography (HPLC), formerly referred to as high-pressure liquid chromatography, is a technique in analytical chemistry used to separate, identify, and quantify each component in a mixture. It relies on pumps to pa ...
,
mass spectrometry
Mass spectrometry (MS) is an analytical technique that is used to measure the mass-to-charge ratio of ions. The results are presented as a '' mass spectrum'', a plot of intensity as a function of the mass-to-charge ratio. Mass spectrometry is u ...
, and
NMR did not lead to positive finding of iGb3 in major organs of mouse, pig, and human species, except trace amount in thymus and immune cells, suggesting a selection pressure during evolution. Obviously, the immune selection pressure against iGb3 is mechanistically different from the well known anti-alpha-Gal antibodies, which caused the loss of alpha1,3-galactose epitope on glycoproteins in humans, apes, and old world monkeys.
[Macher BA, Galili U. The Galalpha1,3Galbeta1,4GlcNAc-R (alpha-Gal) epitope: a carbohydrate of unique evolution and clinical relevance. Biochim Biophys Acta. 2008 Feb;1780(2):75-88.] The disappearance of iGb3 in pig and mouse species cannot be attributed to anti-alpha-Gal antibodies which are absent in these animals.
References
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Glycolipids