Probable biosynthetic pathway for the synthesis of the B antigen for Bh variants.
Red cells and serum from two Bh variants (B+H-cells) have been investigated for B and H blood group glycosyltransferases. The H enzyme could not be detected using either type 1 or type 2 chain acceptors. The B enzyme was present in normal amount when 2'-fucosyllactose was used as substrate, neither 6'-fucosyllactose nor 6'-fucosyllactosamine could act as acceptors for the B enzyme. Upon treatment of the Bh red cells by the B-degrading enzyme from Trichomonas foetus the B antigen was destroyed while H determinants were uncovered (B-H + cells). The cells thus treated could be further converted into A&H-red cells by the action of the A transferase from human blood group A serum. Previous treatment of the B-H + cells by the H-degrading enzyme from T. foetus, however, led to B-/-erythrocytes and prevented their conversion into A red blood cells by the A enzyme. The results clearly demonstrate that, as found in normal B individuals, the B antigen from Bh cells is built up from the H precursor and provide additional evidence that H is not a completely silent gene in Bh individuals.
D000017:ABO Blood-Group System / Q000235:genetics; D005646:Fucosyl Galactose alpha-N-Acetylgalactosaminyltransferase / Q000097:blood; D005647:Fucosyltransferases / Q000097:blood; D014644:Genetic Variation; D006026:Glycoside Hydrolases / Q000494:pharmacology; D006385:Hemagglutination Inhibition Tests; D006801:Humans; D037102:Lectins; D009844:Oligosaccharides / Q000494:pharmacology; D014176:Protein Biosynthesis; D014244:Trichomonas
D000017:ABO Blood-Group System; D037102:Lectins; D009844:Oligosaccharides; D005647:Fucosyltransferases; D005646:Fucosyl Galactose alpha-N-Acetylgalactosaminyltransferase; D006026:Glycoside Hydrolases