Congenital disorders of glycosylation (CDGs) affects multiple tissues and organs in the body. CDG involves any part of the body and almost always has an important nervous system component. CDG can be associated with a variety of adverse symptoms, ranging from mild to severe, and even disabling or life-threatening. CD BioGlyco provides comprehensive and deep insights into disorders of lipid glycosylation. We offer advanced analysis services, including but not limited to Phosphosphingolipid Analysis, Ganglioside Analysis, and Sulfoglycosphingolipid Analysis.
The ST3GAL5 gene encodes sialyltransferase, also known as GM3 synthase, a glycosylphospholipid (sialyl-lactoylceramide) that is enriched in neural tissue. GM3 is a substrate for further reactions that produce the major complex gangliosides in neural tissue. Gangliosides promote neuronal function by indirectly regulating a variety of cell signaling activities through direct interaction with carbohydrate-binding proteins and through differentiation into specialized membrane domains.
The chemical reaction of the GM3 synthase, encoded by the ST3GAL5 gene, is the first step in the production of ganglioside-derived fat molecules. Gangliosides are found on cell and tissue surfaces throughout the body and are especially abundant in the nervous system. Studies have shown that these molecules help regulate chemical signaling pathways that affect cell growth and division, cell motility, cell adhesion to each other, and cell survival. Gangliosides may contribute to normal brain development. Thus, loss of ST3GAL5 activity would significantly affect brain ganglioside production and diversity.
Fig.1 Glycosphingolipid biosynthetic pathways. (Boccuto, et al.,2014)
The A4GALT gene, responsible for encoding Pk synthase, 4-α-galactosyltransferase, is located on chromosome 22q13.2. 4-α-galactosyltransferase catalyzes the transfer of galactose to galactose residues on lactosylceramides, resulting in Pk antigens (globular triacylceramides, Gb3, or CD77). Different mutations in A4GALT have been found to cause a Pk-deficient p phenotype. Studies have shown that the glycosyltransferase encoded by the A4GALT gene is important in transfusion medicine, obstetrics, and pathogen susceptibility. In addition, the A4GALT gene contains three polymorphic nucleotide positions, one missense mutation, 109A>G, and two silent mutations, 903G>C and 987G>A, which can be altered without affecting enzymatic activity.
Fig.2 Scheme representing the biosynthesis of Pk, P and P1 antigens and some other related structures, such as the blood group H, A, and B antigens. (Thuresson, et al., 2011)
β-1-4-Acetylgalactosylaminoacyltransferase 1 is a GM2/GD2 synthase involved in the expression of GM2 and GD2 gangliosides, which are glycosphingolipids containing sialic acid, located in the outer lobe of the plasma membrane and abundantly present in the central nervous system. β-1-4-Acetylgalactosylaminoacyltransferase catalyzes the transfer of GalNAc to lacer, monosiaganglioside (GM3), disialganglioside (GD2) or trisiaganglioside (GT3). Mutation of B4GALNT1 results in loss of GM3 synthase activity, affecting a key branch point in the glycosphingolipid biosynthetic pathway and nervous system signaling.
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