Human red cell Aquaporin CHIP: I. Molecular characterization of ABH and Colton blood group antigens

Barbara L. Smith, Gregory M. Preston, Frances A. Spring, David J. Anstee, Peter Agre

Research output: Contribution to journalArticlepeer-review

98 Scopus citations


Blood group antigens are structural variants in surface carbohydrate or amino acid polymorphisms on extracellular domains of membrane proteins. The red cell water channel-forming integral protein (Aquaporin CHIP) is a homotetramer with only one N-glycosylated subunit, however no CHIP-associated blood group antigens have yet been identified. Immunoblotting, monosaccharide composition analysis, and selective glycosidase digestions revealed that the CHIP-associated oligosaccharide contains ABH determinants and resembles a band 3-type glycan that cannot be cleaved from intact membranes by Peptide:N-glycosidase F. The molecular structure of the Colton antigens was previously unknown, but CHIP was selectively immunoprecipitated with anti-Coa or anti-Cob. The DNA sequence from Colton-typed individuals predicted that residue 45 is alanine in the Co(a+b-) phenotype and valine in the Co(a-b+) phenotype. The nucleotide polymorphism corresponds to a PflMI endonuclease digestion site in the DNA from Co(a-b+) individuals. These studies have defined antigens within two blood group systems on CHIP: (a) an ABH-bearing polylactosaminoglycan attached to a poorly accessible site in the native membrane; and (b) the Colton antigen polymorphism which may permit the identification of rare individuals with defective water channel expression.

Original languageEnglish (US)
Pages (from-to)1043-1049
Number of pages7
JournalJournal of Clinical Investigation
Issue number3
StatePublished - Sep 1994


  • Blood group antigens
  • Erythrocyte membrane
  • Membrane protein glycosylation
  • Water channels

ASJC Scopus subject areas

  • Medicine(all)


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