A large DNA-binding nuclear protein with RNA recognition motif and serine/arginine-rich domain.
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.
Inagaki
H
H
Graduate Program of Biochemical Regulation, School of Agricultural Sciences, Nagoya University, Japan.
Matsushima
Y
Y
Nakamura
K
K
Ohshima
M
M
Kadowaki
T
T
Kitagawa
Y
Y
D000595:Amino Acid Sequence; D000818:Animals; D001120:Arginine / Q000378:metabolism*; D001483:Base Sequence; D002467:Cell Nucleus / Q000378:metabolism; D003001:Cloning, Molecular; D018076:DNA, Complementary; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D007150:Immunohistochemistry; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000235:genetics* / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D051381:Rats; D017386:Sequence Homology, Amino Acid; D012694:Serine / Q000378:metabolism*; D014157:Transcription Factors; D014407:Tumor Cells, Cultured
D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D016601:RNA-Binding Proteins; D014157:Transcription Factors; C099656:ZNF638 protein, human; D012694:Serine; D001120:Arginine