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Vox Sang. 2000;79(4):219-26.

Characterization of the histo-blood group O(2) gene and its protein product.

Author information

1
Institute of Molecular Pathology and Immunology of University of Porto, IPATIMUP, Porto, Portugal.

Abstract

BACKGROUND AND OBJECTIVES:

This study aimed to show the full sequence and function of the O(2) allele, and investigate whether it accounts for the incompatible expression of A antigens in gastric carcinomas of blood group O persons.

MATERIALS AND METHODS:

By PCR, we determined the ABO genotype of group O subjects (76 gastric carcinoma patients and 165 blood donors). Two expression constructs, encoding either the putative soluble or full-length O(2) protein, were used to transfect Sf9 cells. The expression and the activity of the O(2) protein were analysed by immunohistochemistry and enzymatic assays, respectively.

RESULTS:

No significant difference was detectable between the O(2) allele frequency in gastric carcinoma patients (3.9%) and blood donors (4.2%). Sequencing analysis of the O(2) allele revealed an intact reading frame identical to that of A transferase except for four nucleotide substitutions. O(2)-transfected Sf9 cells and gastric carcinomas genotyped as O(1)O(2) both expressed a protein recognized by anti-A/B transferase monoclonal antibodies. In enzymatic assays, the O(2) protein failed to show measurable A transferase activity.

CONCLUSION:

The O(2) allele has an intact reading frame encoding a protein immunologically related to A/B transferases and enzymatically inactive. Further, our data gave no indication that the O(2) allele is related to the phenomenon of incompatible A antigen expression in gastric cancer.

PMID:
11155073
DOI:
10.1159/000056734
[Indexed for MEDLINE]

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