Communicated by: Fumio Hanaoka
Terminal deoxynucleotidyltransferase directly interacts with a novel nuclear protein that is homologous to p65
Article first published online: 20 DEC 2001
Genes to Cells
Volume 6, Issue 7, pages 641–652, July 2001
How to Cite
Yamashita, N., Shimazaki, N., Ibe, S., Kaneko, R., Tanabe, A., Toyomoto, T., Fujita, K., Hasegawa, T., Toji, S., Tamai, K., Yamamoto, H. and Koiwai, O. (2001), Terminal deoxynucleotidyltransferase directly interacts with a novel nuclear protein that is homologous to p65. Genes to Cells, 6: 641–652. doi: 10.1046/j.1365-2443.2001.00449.x
- Issue published online: 20 DEC 2001
- Article first published online: 20 DEC 2001
- Received: 18 April 2001Accepted: 28 April 2001
Background Terminal deoxynucleotidyltransferase (TdT) is a DNA polymerase that enhances Ig and TcR gene diversity in the N region in B- and T-cells. TdT is found as a member of a large protein complex in the lysate of the thymocytes. To elucidate the molecular mechanism of the synthesis of the N region, we first attempted to isolate the genes with products that are interacting directly with TdT.
Results Using a yeast two-hybrid system, we isolated a cDNA clone encoding a novel nuclear protein that interacts with TdT. This protein was designated as TdT interacting factor 1 (TdIF1). TdIF1 has a high degree of homology to the transcription factor p65, which belongs to the nuclear receptor superfamily. TdIF1 contains HMG-I and HMG-Y DNA binding domains (AT-hooks) and can bind to single- and double-stranded DNA. TdT and TdIF1 were co-eluted at position 232 kDa by gel filtration of MOLT4 lysate. TdIF1 can enhance TdT activity fourfold in vitro assay system using oligo(dT)16 as primers.
Conclusions TdIF1 binds directly to TdT, both in vitro and in vivo. TdIF1 and TdT exist as the members of a 232 kDa protein complex. TdIF1 can enhance TdT activity maximum fourfold in vitro assay system, suggesting that it positively regulates the synthesis of the N region during V(D)J recombination in the Ig and TcR genes.