Characterization of a hepatoma mRNA transcribed from a third promoter of a 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase-encoding gene and controlled by ets oncogene-related products.

6-Phosphofructo-2-kinase (EC 2.7.1.105)/fructose-2,6-bis-phosphatase (EC 3.1.3.46) catalyzes the synthesis and degradation of fructose 2,6-bisphosphate, a ubiquitous stimulator of glycolysis. The liver (L-type) and muscle (M-type) mRNAs for this bifunctional enzyme arise from distinct promoters of the same gene. We have now characterized in rat hepatoma FTO2B cells another mRNA, which is transcribed from a third promoter of that gene. This F-type mRNA is present in fetal rat liver and muscle, in rat placenta, and in several established rat cell lines. The F promoter contains no TATA box but contains several binding sites for Sp1 and for members of the ets oncogene family. Transfection of FTO2B cells with constructs containing the intact or mutagenized F promoter showed that its activity depends mainly on one of these sites. This site bound a heteromeric FTO2B cell protein indistinguishable from the ets-related GA binding protein alpha/ankyrin-repeats GA binding protein beta transcription factor.