Nucleolar protein p120 contains an arginine-rich domain that binds to ribosomal RNA.
Human proliferation-associated protein p120 has previously been shown to localize to the nucleolus, and several functional domains of p120 have been elucidated. By using a nitrocellulose filter binding assay and a Northwestern blotting procedure this study shows that recombinant p120 binds to an rRNA fragment in vitro with a dissociation constant of 4 nM. The specific RNA-binding region of p120 (residues 1-57) was identified with glutathione S-transferase-fused p120 deletion constructs and Northwestern blotting procedures. This RNA-binding region of p120, which includes the nucleolar localization signal of p120, is similar to the arginine-rich RNA-binding regions found in other RNA-binding proteins such as HIV Rev and Tat. Experiments in vivo with HeLa cell nucleolar extracts showed that p120 was associated with the 60-80S pre-ribosomal particles. This association is disrupted by treatment with either RNase A or buffer of high ionic strength. These results suggest that p120 might be involved in rRNA/ribosome maturation, consistent with the role of the yeast homologue Nop2p in rRNA biogenesis.
Gustafson
W C
WC
Department of Pharmacology, Baylor College of Medicine, 1 Baylor Plaza, Houston, TX 77030, USA.
Taylor
C W
CW
Valdez
B C
BC
Henning
D
D
Phippard
A
A
Ren
Y
Y
Busch
H
H
Durban
E
E
D000595:Amino Acid Sequence; D001120:Arginine / Q000032:analysis*; D001665:Binding Sites; D001667:Binding, Competitive; D015152:Blotting, Northern; D015153:Blotting, Western; D002466:Cell Nucleolus / Q000737:chemistry; D017353:Gene Deletion; D005982:Glutathione Transferase / Q000235:genetics; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009687:Nuclear Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D011498:Protein Precursors / Q000378:metabolism; D012335:RNA, Ribosomal / Q000378:metabolism*; D011993:Recombinant Fusion Proteins; D011994:Recombinant Proteins / Q000378:metabolism; D012261:Ribonucleoproteins / Q000378:metabolism; D012359:tRNA Methyltransferases
D009687:Nuclear Proteins; D011498:Protein Precursors; D012335:RNA, Ribosomal; D011993:Recombinant Fusion Proteins; D011994:Recombinant Proteins; D012261:Ribonucleoproteins; D001120:Arginine; C065028:NOP2 protein, human; D012359:tRNA Methyltransferases; D005982:Glutathione Transferase