Sequence-specific DNA-binding proteins within the Mbcr on the Ph1 chromosome.

The Philadelphia1 (Ph1) chromosome results from a reciprocal translocation between chromosome 9 and chromosome 22, which fuses a portion of the ABL oncogene to the BCR gene, forming the BCR/ABL fusion gene. This produces a fusion protein with a greatly increased protein tyrosine kinase activity in comparison to that of the normal ABL protein. The BCR/ABL gene is transcribed from the promoter of the normal BCR gene, but little is known about the regulation of its expression. In this study, we asked whether there are sequence-specific DNA-binding proteins (DBP) that bind to the breakpoint cluster region (bcr, or Mbcr) within the BCR gene. Sequence-specific DBP located within the Mbcr could have a transcription-regulating effect, and they could participate in the recombination that generates BCR/ABL. Our data show that there are sequence-specific DBP that bind within the Mbcr.