Purification and cDNA cloning of HeLa cell p54nrb, a nuclear protein with two RNA recognition motifs and extensive homology to human splicing factor PSF and Drosophila NONA/BJ6.
While searching for a human homolog of the S.cerevisiae splicing factor PRP18, we found a polypeptide that reacted strongly with antibodies against PRP18. We purified this polypeptide from HeLa cells using a Western blot assay, and named it p54nrb (for nuclear RNA-binding protein, 54 kDa). cDNAs encoding p54nrb were cloned with probes derived from partial sequence of the purified protein. These cDNAs have identical coding sequences but differ as a result of alternative splicing in the 5' untranslated region. The cDNAs encode a 471 aa polypeptide that contains two RNA recognition motifs (RRMs). Human p54nrb has no homology to yeast PRP18, except for a common epitope, but is instead 71% identical to human splicing factor PSF within a 320 aa region that includes both RRMs. In addition, both p54nrb and PSF are rich in Pro and Gln residues outside the main homology region. The Drosophila puff-specific protein BJ6, one of three products encoded by the alternatively spliced no-on-transient A gene (nonA), which is required for normal vision and courtship song, is 42% identical to p54nrb in the same 320 aa region. The striking homology between p54nrb, PSF, and NONA/BJ6 defines a novel phylogenetically conserved protein segment, termed DBHS domain (for Drosophila behavior, human splicing), which may be involved in regulating diverse pathways at the level of pre-mRNA splicing.
Dong
B
B
Cold Spring Harbor Laboratory, NY 11724-2208.
Horowitz
D S
DS
Kobayashi
R
R
Krainer
A R
AR
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D015139:Blotting, Southern; D003001:Cloning, Molecular; D004247:DNA; D004268:DNA-Binding Proteins; D004330:Drosophila; D029721:Drosophila Proteins; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D034521:Nuclear Matrix-Associated Proteins; D009687:Nuclear Proteins / Q000235:genetics* / Q000302:isolation & purification; D050810:Octamer Transcription Factors; D000072670:PTB-Associated Splicing Factor; D016601:RNA-Binding Proteins / Q000235:genetics* / Q000302:isolation & purification; D017386:Sequence Homology, Amino Acid
D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; C070174:NONA protein, Drosophila; C083214:NONO protein, human; D034521:Nuclear Matrix-Associated Proteins; D009687:Nuclear Proteins; D050810:Octamer Transcription Factors; D000072670:PTB-Associated Splicing Factor; D016601:RNA-Binding Proteins; D004247:DNA