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Characterization of the Histo‐Blood Group O 2 Gene and Its Protein Product
Author(s) -
Amado Margarida,
Bennett Eric P.,
Carneiro Fátima,
Clausen Henrik
Publication year - 2000
Publication title -
vox sanguinis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.68
H-Index - 83
eISSN - 1423-0410
pISSN - 0042-9007
DOI - 10.1046/j.1423-0410.2000.7940219.x
Subject(s) - microbiology and biotechnology , abo blood group system , allele , biology , open reading frame , antigen , antibody , transfection , sf9 , genotype , gene , exon , monoclonal antibody , recombinant dna , biochemistry , genetics , peptide sequence , spodoptera
AbstractBackground 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.