InterPro domain: IPR007015

Proteins of this family are predominantly nucleolar. Myb-binding protein 1A (MYBBP1A) is a transcription regulator that may play an important role in the cellular stress response [ 1 , 2 , 3 ]. This family also includes the fifth essential DNA polymerase (Pol5p) of Schizosaccharomyces pombe (Fission yeast) and Saccharomyces cerevisiae (Baker's yeast) ( 2.7.7.7 ). Pol5p is localized exclusively to the nucleolus and binds near or at the enhancer region of rRNA-encoding DNA repeating units [ 4 ]. Despite its name, Pol5 is unrelated to any known polymerase. Both Pol5p and MYBBP1A are thought to function as regulators of rDNA transcription, and may have other functions [ 5 ].

1. Myb-binding protein 1a augments AhR-dependent gene expression. J. Biol. Chem. 277, 22515-9
2. Molecular characterization of Mybbp1a as a co-repressor on the Period2 promoter. Nucleic Acids Res. 37, 1115-26
3. The nucleolar protein Myb-binding protein 1A (MYBBP1A) enhances p53 tetramerization and acetylation in response to nucleolar disruption. J. Biol. Chem. 289, 4928-40
4. The fifth essential DNA polymerase phi in Saccharomyces cerevisiae is localized to the nucleolus and plays an important role in synthesis of rRNA. Proc. Natl. Acad. Sci. U.S.A. 99, 9133-8
5. Yeast POL5 is an evolutionarily conserved regulator of rDNA transcription unrelated to any known DNA polymerases. Cell Cycle 2, 120-2