Gene targeting experiments have revealed that transcription factors such as
c-Myb and GATA-1 play crucial roles during hematopoietic differentiation.
c-Myb is necessary in the immature cells of almost every hematopoietic line
age and GATA-1 is essential for the development of the ervthroid lineage. I
n addition, CREB-binding protein (CBP) acts as a transcriptional adapter fo
r various transcription factors, including c-Myc and GATA-1. In this paper,
,ve show that the transcription factors c-Myb and GATA-1 each inhibit the t
ranscriptional activity of the other and that any possible bipartite comple
xes c-Myb, GATA-1, and CBP could be formed, but the tripartite complex was
hardly formed, The exclusive binding of GATA-1 and c-Myb to CBP is probably
the molecular basis for the mutual inhibition of their transcriptional act
ivity. Our data suggest that cross-talk between these three factors might b
e important for hematopoietic differentiation and that CBP functions as a h
ey molecule during the process.