Nucleolar protein B23.1 binds to retinoblastoma protein and synergistically stimulates DNA polymerase alpha activity.

摘要: Phosphorylated retinoblastoma protein and nucleolar B23 are putative stimulatory factors for DNA polymerase alpha. We showed that these two interacted with each other stimulated the activity of alpha synergistically. exists in isoforms designated as B23.1 B23.2. While bound to a protein-conjugated column, B23.2 did not. These results indicate can directly bind protein. It was also shown co-immunoprecipitated both from HeLa cell extract by monoclonal antibodies raised against components. suggest three proteins exist complex cells, at least part. The simultaneous addition caused stimulation is much higher than sum alone. maximal attained molar ratio alpha/retinoblastoma protein/B23.1 = 1:1:12. Since hexamer solution, it may act stimulator form double-hexamer, concert phosphorylated