MOLECULAR-CLONING OF A RAT 49-KDA TBP-INTERACTING PROTEIN (TIP49) THAT IS HIGHLY HOMOLOGOUS TO THE BACTERIAL RUVB

TBP as a central component in transcriptional regulation can form comp lexes with various regulatory factors. Using histidine-tagged TBP for affinity-purification of TBP-bound proteins, we isolated a 49-kD prote in termed TBP-interacting protein 49 (TIP49) from rat liver nuclear ex tracts, We cloned the entire cDNA of TIP49 encoding a novel polypeptid e of 456 amino acids, and thereafter established an FM3A cell line tha t constitutively expressed an epitope-tagged TBP. Immunoprecipitation analysis of the cell extracts indicated that TIP49 and TBP were presen t in an identical complex. Interestingly, the amino acid sequence of T IP49 exhibited high similarity to those sequences of the RuvB bacteria l recombination factors which direct branch migration of the Holliday junction and contain the Walker A and B motifs responsible for ATP bin ding and ATP hydrolysis. These findings suggest that TIP49 is a putati ve ATP-dependent DNA helicase. (C) 1997 Academic Press.