![]() The Se allele encodes another α-1,2-fucosyltransferase (FUT2) that uses Type I and Type III precursors as acceptors to form the H antigen in the epithelia of the gastrointestinal, respiratory, and reproductive tracts, and salivary glands, as well as modifying milk oligosaccharides to generate the H antigen 9. The H allele encodes an α-1,2-fucosyltransferase (FUT1) that transfers a fucose residue to Type II and Type IV glycan units to form the H antigen on erythrocytes and vascular endothelial cells 9. ![]() Two fucosyltransferases are involved in this reaction. ![]() Blood group antigen synthesis is initiated by the addition of a fucose residue to a common precursor glycan chain (six different types are known) to obtain the H antigen 10, 11. The A, B, and H antigens are formed by the sequential action of glycosyltransferases encoded by three genetic loci, the ABO, H, and Secretor, now termed the ABO, FUT1, and FUT2 loci 9. The antigens are classified as A, B, or H and subclassified depending on the sugar composition and the variety of linkages 8 (Fig. 90%) and, to a lesser extent, to lipids (ca. Discovered in 1900 by Karl Landsteiner through agglutination tests, the antigens present in these groups are composed of specific oligosaccharides mainly linked to proteins (ca. The most well-known and clinically relevant blood groups are ABO. Up to date, and besides their importance, the physiological functions of several blood group antigens are still unknown. They are also widely distributed throughout the human body such as the salivary glands, gastrointestinal and urinary tracts, and respiratory cavities 4. The blood group antigens are not restricted solely to red blood cells (RBCs) or even to hematopoietic tissues. The 43 systems are genetically determined by 48 genes ( ). There are currently 43 recognized blood group systems containing 345 red cell antigens. They are based either on oligosaccharide epitopes, including the ABO, P, and Lewis antigens, or specific amino acid sequences, such as Rh, Kell, and Duffy antigens 3. Blood group antigens are assigned to blood group systems based on their relationship to each other as determined by serological or genetic criteria 1, 2. Furthermore, using agglutination tests and flow cytometry-based techniques, we demonstrate the ability of FucOB to convert universal O type into rare Bombay type blood, providing exciting possibilities to facilitate transfusion in recipients/patients with Bombay phenotype.īlood group antigens play fundamental roles not only in blood transfusion but also in organ transplantation. The structural data together with site-directed mutagenesis, enzymatic activity and computational methods provide molecular insights into substrate specificity and catalysis. X-ray crystal structures of FucOB show a three-domain architecture, including a GH95 glycoside hydrolase. We discover FucOB from the mucin-degrading bacteria Akkermansia muciniphila as an α-1,2-fucosidase able to hydrolyze Type I, Type II, Type III and Type V H antigens to obtain the afucosylated Bombay phenotype in vitro. Recipients with the rare total deficiency in H antigen, the O h Bombay phenotype, can only be transfused with group O h blood to avoid serious transfusion reactions. ![]() Red blood cell antigens play critical roles in blood transfusion since donor incompatibilities can be lethal.
0 Comments
Leave a Reply. |