Expression of the developmental I antigen by a cloned human cDNA encoding a member of a beta-1,6-N-acetylglucosaminyltransferase gene family

Genes Dev. 1993 Mar;7(3):468-78. doi: 10.1101/gad.7.3.468.


The blood group i/I antigens were the first identified alloantigens that display a dramatic change during human development. The i and I antigens are determined by linear and branched poly-N-acetyllactosaminoglycans, respectively. In human erythrocytes during embryonic development, the fetal (i) antigen is replaced by the adult (I) antigen as a result of the appearance of a beta-1,6-N-acetylglucosaminyltransferase, the I-branching enzyme. Here, we report the cDNA cloning and expression of this branching enzyme that converts linear into branched poly-N-acetyllactosaminoglycans, thus introducing the I antigen in transfected cells. The cDNA sequence predicts a protein with type II membrane topology as has been found for all other mammalian glycosyltransferases cloned to date. The Chinese hamster ovary cells that stably express the isolated cDNA acquire I-branched structures as evidenced by the structural analysis of glycopeptides from these cells. Comparison of the amino acid sequence with those of other glycosyltransferases revealed that this I-branching enzyme and another beta-1,6-N-acetylglucosaminyltransferase that forms a branch in O-glycans are strongly homologous in the center of their putative catalytic domains. Moreover, the genes encoding these two beta-1,6-N-acetylglucosaminyltransferases were found to be located at the same locus on chromosome 9, band q21. These results indicate that the I-branching enzyme represents a member of a beta-1,6-N-acetylglucosaminyltransferase gene family of which expression is controlled by developmental programs.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adult
  • Animals
  • CHO Cells
  • Carbohydrate Sequence
  • Chromosome Banding
  • Chromosome Mapping
  • Chromosomes, Human, Pair 9*
  • Cloning, Molecular / methods
  • Cricetinae
  • DNA / genetics*
  • DNA / metabolism
  • Embryonic and Fetal Development / physiology
  • Erythrocytes / enzymology
  • Glycopeptides / biosynthesis
  • Glycopeptides / isolation & purification
  • Humans
  • I Blood-Group System / genetics*
  • Isoantigens / genetics*
  • Molecular Sequence Data
  • Multigene Family*
  • N-Acetylglucosaminyltransferases / genetics*
  • N-Acetylglucosaminyltransferases / metabolism
  • Sequence Homology, Nucleic Acid
  • Transfection


  • Glycopeptides
  • I Blood-Group System
  • Isoantigens
  • DNA
  • N-Acetylglucosaminyltransferases
  • alpha-1,6-mannosylglycoprotein beta 1,6-N-acetylglucosaminyltransferase

Associated data

  • GENBANK/L06452
  • GENBANK/L11593
  • GENBANK/L11594
  • GENBANK/L16016
  • GENBANK/L24529
  • GENBANK/S56762
  • GENBANK/S56763
  • GENBANK/Z15047
  • GENBANK/Z15048
  • GENBANK/Z19550