NBP-45, a novel nucleosomal binding protein with a tissue-specific and developmentally regulated expression

Hitoshi Shirakawa, David Landsman, Yuri V. Postnikov, Michael Bustin

Research output: Contribution to journalArticlepeer-review

46 Citations (Scopus)


Here we characterize a novel murine nuclear protein, which we named NBP- 45, that is related to the ubiquitous nuclear proteins HMG-14/-17, binds specifically to nucleosome core particles, and can function as a transcriptional activator. NBP-45 mRNA is expressed at low levels and in variable amounts in all mouse tissues tested but is especially abundant in RNA extracted from 7-day-old mouse embryos, suggesting that it functions in early embryonic development. NBP-45 is composed of 406 amino acids and is encoded by a single size transcript. The region spanning the N-terminal 85 amino acids contains three segments that are highly homologous to functionally important domains in the HMG-14/-17 protein family: the nuclear localization signal, the nucleosome binding domain, and the chromatin unfolding domain. The protein region spanning the C-terminal 321 amino acids has a 42% content of negatively charged residues. The first 23 amino acids contain a region necessary for nuclear entry of the protein, the region spanning residues 12-40 is the main nucleosomal binding domain of the protein, and the negatively charged, C-terminal domain is necessary for transcription activation. The functional domains of NBP-45 are indicative of a nuclear protein that binds to nucleosomes, thereby creating a chromatin region of high local negative charge. Our studies establish the nucleosomal binding domain as a protein motif that is present in other than just the ubiquitous HMG-14/-17 proteins. We suggest that the nucleosomal binding domain motif is a protein module that facilitates binding to nucleosomes in chromatin.

Original languageEnglish
Pages (from-to)6368-6374
Number of pages7
JournalJournal of Biological Chemistry
Issue number9
Publication statusPublished - 2000 Mar 3
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology


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