The rat poly pyrimidine tract binding protein (PTB) interacts with a single-stranded DNA motif in a liver-specific enhancer.

We characterized and purified a protein from rat liver which specifically binds to a DNA motif present in a liver-specific enhancer of the rat tyrosine aminotransferase (TAT) gene, when offered as single-stranded DNA. Binding is highly sequence-specific and coincides with a region known to be essential for function of the enhancer. Microsequencing revealed that this protein is the rat homologue of the mouse and human poly Pyrimidine Tract binding protein (PTB), which has been shown to bind to premRNA and may participate in RNA splicing. This finding was corroborated by subsequent Western blot experiments using a PTB-specific antibody. These findings indicate a possible dual role for this protein in RNA processing and transcription.