A large DNA-binding nuclear protein with RNA recognition motif and serine/arginine-rich domain

Hidetoshi Inagaki, Yuichi Matsushima, Kazuyasu Nakamura, Mikiko Ohshima, Tatsuhiko Kadowaki, Yasuo Kitagawa

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35 Citations (Scopus)


cDNA species encoding a large DNA-binding protein (NP220) of 1978 amino acids was isolated from human cDNA libraries. Human NP220 binds to double- stranded DNA fragments by recognizing clusters of cytidines. Immunofluorescent microscopy with antiserum directed against NP220 revealed a punctate or 'speckled' pattern and coiled body-like structures in the nucleoplasm of various human cell lines. These structures diffused in the cytoplasm during mitosis. Western blot analysis showed that NP220 is enriched in the lithium 3,5-diiodosalicylate-insoluble fraction of nuclei. The domain essential for DNA binding is localized in C-terminal half of NP220. Human NP220 shares three types of domains (MH1, MH2, and MH3) with the acidic nuclear protein, matrin 3 (Belgrader, P., Dey, R., and Berezney, R. (1991) J. Biol. Chem. 266, 9893-9899). MH1 is a 48-amino acid sequence near the N terminus of both human NP220 and rat matrin 3. MH2 is a 75-amino acid sequence homologous to the RNA recognition motifs of heterogeneous nuclear RNP I and L. It is repeated three times in NP220 and twice in matrin 3. MH3 is a 60-amino acid sequence at the C terminus of both NP220 and matrin 3. NP220 has an arginine/serine-rich domain commonly found in pre-mRNA splicing factors. Close to the domain essential for DNA binding, there are nine repeats of the sequence LVTVDEVIEEEDL. Thus, NP220 is a novel type of nucleoplasmic protein with multiple domains.

Original languageEnglish
Pages (from-to)12525-12531
Number of pages7
JournalJournal of Biological Chemistry
Issue number21
Publication statusPublished - 1996
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology
  • Cell Biology


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