Phosphorylation of the N-terminal domain of Xenopus TATA-box binding protein by DNA-dependent protein kinase depends on the C-terminal core domain.

DNA-dependent protein kinase (DNA-PK) has been shown to phosphorylate several transcription factors in vitro, suggesting that this nuclear enzyme - in addition to its role in DNA repair and recombination - may be involved in transcriptional regulation. In the typical mechanism the DNA-bound kinase phosphorylates a substrate that is bound to the same DNA molecule. Here I report that the Xenopus TATA-box binding protein (xTBP) is hyperphosphorylated by DNA-PK in vitro. The phosphorylation is in the N-terminal domain of the protein but depends fully on the presence of the C-terminal core domain.