Figure 2.

Start site mapping and characterization of the Gfi1b promoter. (a) Primer extension on bone marrow and spleen cells from wt and Gfi1b transgenic mice. The primer for the primer extension analysis hybridizes to the sense strand from nucleotides +34 to +13 in the first exon of the Gfi1b gene. Two major start sites were conserved in bone marrow and spleen of wt mice, marked by arrows. The more distal start could not be observed in bone marrow RNA from Gfi1b transgenic mice. No products were observed in the yeast t-RNA control. (b) Analysis of the mouse, rat and human Gfi1b promoter. Nucleotide sequence alignment of the mouse, human and rat Gfi1b core promoter sequences. Numbers above the lines are the nucleotide numbers starting with +1 at the 5′ end of the murine cDNA. Homology of the mouse, rat and human Gfi1b promoter sequences was analyzed using the MultAlin interface software (31). Marked in bold letters in the consensus line are the core sequences of the binding sites for the transcription factors GATA, NF-Y that have been described previously (19) and the tandem Gfi1b-binding site (boxed). The arrow above the mGfi1b sequence marks the shortest primer extension product found in bone marrow and spleen (see Figure 2a). The arrow under the hGfi1b sequence marks the previously described mRNA start site for the human Gfi1b (19). Underlined is the most 5′ end of the published cDNA for Gfi1b. The long arrow marks the localization of the primer used for the primer extension experiments.