Human Biochemistry, Volume 2 - Murray R. 1993
Special Topics
Glycoproteins and Proteoglycans
Glycoproteins - H Locus
The H locus encodes fucosyltransferase in hematopoietic Tissues, which attaches a fucose residue via an α-1,2 linkage to a Gal residue, which in turn is attached to the oligosaccharide via a ß-1,4 or ß-1,3 linkage. Fucosyltransferase catalyzes the reaction
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Table 54.7. Four independent Gene systems determining the expression of ABH(O) and Lewis (Le) Blood Group Antigens
|
Genetic locus |
Alleles |
|
H |
H,h |
|
Secretor |
Se,se |
|
ABO |
A,B,O |
|
Lewis |
Le,le |
The product of this reaction, Fuc-α 1,2-Gal-ß—R, serves as a precursor for both A and B erythrocyte oligosaccharide antigens. The h allele of the H locus encodes an inactive fucosyltransferase; consequently, individuals with the hh genotype fail to produce this essential precursor and have blood group O, even though genes encoding active A or B Glycosyltransferases may be present in such individuals.
Last update: 06/08/2026
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