title: Tissue-dependent expression of two (alpha 1----2)-fucosyltransferases specified by the H and Se genes.
abstract: Human blood group H substance is produced from its percursor by the action of (alpha 1----2)-fucosyltransferase. In a classical model, the Se gene that determines secretor status is a regulatory gene controlling the expression of H gene-specified fucosyltransferase in the secretory tissues. However, recent biochemical evidence supports a new genetic model in which the H and Se genes are both structural genes encoding two fucosyltransferases with different characteristics. The H gene-specified enzyme (H enzyme) is absent in secretory tissues and secretory fluids, while the Se gene-specified enzyme (Se enzyme) is missing in hematopoietic tissues. The H enzyme has a much lower Km for phenyl-beta-galactoside than does the Se enzyme. The tissue-dependent expression of the two enzymes was examined according to this criteria. The H enzyme was found to be predominant in the tissues of secretors examined (lung, liver, kidney, stomach, and skeletal muscle). While the Se enzyme exists in the secretor's lung, liver and kidney, very little or none is found in the stomach and skeletal muscle tissues.
mesh_terms: D000017:ABO Blood-Group System / Q000235:genetics; D005647:Fucosyltransferases / Q000235:genetics* / Q000378:metabolism; D005786:Gene Expression Regulation; D005796:Genes; D006602:Hexosyltransferases / Q000235:genetics*; D006801:Humans; D007668:Kidney / Q000201:enzymology; D008099:Liver / Q000201:enzymology; D008168:Lung / Q000201:enzymology; D008957:Models, Genetic; D009132:Muscles / Q000201:enzymology; D013270:Stomach / Q000201:enzymology; D014018:Tissue Distribution; D000097631:Galactoside 2-alpha-L-fucosyltransferase
chemical_list: D000017:ABO Blood-Group System; D005647:Fucosyltransferases; D006602:Hexosyltransferases; D000097631:Galactoside 2-alpha-L-fucosyltransferase