The chicken erythrocyte transcription factor, GATA-1, is associated with several non-DNA binding proteins. We show that GATA-1 multiprotein complexes exist in primitive and definitive erythrocytes. These complexes bind to GATA motifs of the p-globin promoter and histone H5 enhancer with high affinity, and to the chicken β-globin promoter specialized TATA element and enhancer GATA with low affinity. The low affinity β-globin TATA element would allow basal transcription factors to displace the GATA-1 multiprotein complex. Further, our results suggest that p-globin promoter's low affinity Sp1 binding site and reduced levels of Sp1 in definitive cells prevent its expression in these cells.
