Analysis of cooperative expression of the genes encoding glycosyltransferases involved in the histo-blood group ABH antigens.

Moreover, we have confirmed that the ABO gene expression is negatively regulated by N-box upstream of the promoter and that the N box binds with a nuclear factor termed RACP. N-box is recognized by members of bHLH factor. The bHLH family of transcriptional regulators plays crucial roles in the development of various organs and cell types. Previously, we demonstrated that the ABO gene was co-expressed with the FUT1 and FUT2 genes. Inspection of the nucleotide sequences of the upstream region of the FUT1 and FUT2 genes revealed putative binding site of bHLH proteins, suggesting that the bHLH factors could play crucial roles in expression of the genes. Therefore, the N-box binding protein including to the RACP might mediate regulation for cooperative expression of those genes encoding glycosyltransferases involved in the ABH antigens.